Organic light emitting diode, method for manufacturing same, image display device, and illuminating device

ABSTRACT

An organic light emitting diode and a method for manufacturing the same. The organic light emitting diode includes an anodic conductive layer, an organic EL layer, and a cathodic conductive layer formed from Ag or an alloy of Ag, or the like, sequentially laminated on a substrate, such that a two-dimensional lattice structure is provided on a surface of the cathodic conductive layer on an organic EL layer side, an extraction wavelength and a distance between centers of concave portions or convex portions in the two-dimensional lattice structure are within a region surrounded by specific coordinates in a graph illustrating a relationship between the light extraction wavelength and the distance, and the depth of the concave portions or a height of the convex portions is 12 nm to 180 nm.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/882,848, which is the U.S. National Phase under 35 U.S.C. §371 ofInternational Application PCT/JP2011/075285, filed Nov. 2, 2011,designating the U.S., and published in Japanese as WO 2012/060404 on May10, 2012, which claims priority to Japanese Patent Application No.2010-246653, filed Nov. 2, 2010, the contents of which are incorporatedherein by reference in their entireties.

TECHNICAL FIELD

The present invention relates to an organic light emitting diode, amethod for manufacturing the same, and an image display device and anilluminating device that are provided with the organic light emittingdiode.

BACKGROUND ART

An organic light emitting diode is a light emitting device using anorganic electroluminescence (hereinafter, referred to as “organic EL”),and generally, has a configuration in which an anode and a cathode areprovided on both surfaces of an organic EL layer that includes a lightemitting layer containing an organic light emitting material. As theorganic EL layer, an electron transport layer, a hole transport layer,and the like are provided as necessary in addition to the light emittinglayer. Examples of an organic light emitting diode include a bottomemission type in which an anode formed from a transparent conductivematerial such as ITO, an organic EL layer including a light emittinglayer, and a cathode formed from a metal are sequentially formed on atransparent substrate such as a glass substrate, and light is extractedfrom a substrate side, a top emission type in which the cathode, theorganic EL layer, and the anode are sequentially formed on thesubstrate, and light is extracted from a side opposite to the substrateside, and the like.

The organic light emitting diode has advantages in that the viewingangle dependency is small, the power consumption is low, and thethickness thereof is very small. On the other hand, the organic lightemitting diode has a problem in that the light extraction efficiency islow. The light extraction efficiency represents a ratio of energy oflight emitted to the air from a light extraction surface (for example,in a case of a bottom emission type, a substrate surface) to energy oflight emitted from the light emitting layer. For example, light emittedfrom the light emitting layer is output in all directions, and thus thelight enters into a waveguide mode in which the majority thereof repeatstotal reflection on an interface between a plurality of layers havingrefractive indexes different from each other. As a result, the light isconverted into heat while propagating between layers, or emitted from aside surface, and thus the light extraction efficiency decreases. Inaddition, since the light emitting layer is close to the cathode formedfrom a metal, a part of near-field light from the light emitting layeris converted into a surface plasmon on a surface of the cathode, anddisappears. As a result, the light extraction efficiency decreases.

The light extraction efficiency has an effect on brightness of adisplay, an illuminating device, and the like that are provided with theorganic light emitting diode, and thus various methods has been reviewedto improve the light extraction efficiency. As one of the methods ofimproving the light extraction efficiency, a method of using surfaceplasmon resonance is suggested. For example, PTL 1 to PTL 4 disclose amethod of providing a one-directional or two-directional periodicmicrostructure on a surface of a metallic layer (cathode). In thismethod, the periodic microstructure functions as a diffraction lattice.Due to this, energy, which disappears as the surface plasmon on thesurface of the cathode is extracted as light, and thus the lightextraction efficiency is improved.

CITATION LIST Patent Literature

[PTL 1] Japanese Unexamined Patent Application, First Publication No.2002-270891

[PTL 2] Japanese Unexamined Patent Application, First Publication No.2004-31350

[PTL 3] Published Japanese Translation No. 2005-535121

[PTL 4] Japanese Unexamined Patent Application, First Publication No.2009-158478

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, when preparing the periodic microstructure as described above,since there is no information about the distance between the centers ofconcave portions or convex portions that efficiently convert the surfaceplasmon into propagation light, or about structural height in therelated art, it was difficult to maximize the light extractionefficiency.

The invention has been made in consideration of the above-describedcircumstances, and an object thereof is to provide an organic lightemitting diode excellent in light extraction efficiency, a method formanufacturing the same, and an image display device and an illuminatingdevice that are provided with the organic light emitting diode.

Means to Solve the Problems

The present inventors have made a thorough investigation. As a result,they have found that when a two-dimensional periodic microstructure isformed to satisfy specific parameters, the light extraction efficiencymay be significantly improved, and they have completed the invention.

The invention has the following aspects.

[1] An organic light emitting diode in which at least an anodicconductive layer, an organic EL layer that includes a light emittinglayer containing an organic light emitting material, and a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of concaveportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organic EL layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the depth of the concave portions is 12 nm to 180 nm;

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

[2] A method for manufacturing the organic light emitting diodeaccording to [1], the method including: preparing a substrate having astructure in which a plurality of convex portions corresponding to thetwo-dimensional lattice structure are periodically and two-dimensionallyordered on a surface; and sequentially laminating the anodic conductivelayer, the organic EL layer, and the cathodic conductive layer on thestructure.

[3] The method for manufacturing the organic light emitting diodeaccording to [2], wherein the substrate is prepared according to a dryetching method using a particle mono-layer film as an etching mask.

[4] The method for manufacturing the organic light emitting diodeaccording to [2], further including: preparing the substrate using thetwo-dimensional lattice structure as a mold, wherein the mold is amaster mold that is manufactured according to the dry etching methodusing the particle mono-layer film as the etching mask, or a metallicelectroformed mold or resin mold that is obtained by transfer of themaster mold.

[5] An organic light emitting diode in which at least a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag, an organic EL layer that includes a light emitting layercontaining an organic light emitting material, and an anodic conductivelayer are sequentially laminated on a substrate, and a two-dimensionallattice structure, in which a plurality of concave portions areperiodically and two-dimensionally ordered, is provided on a surface ofthe cathodic conductive layer on an organic EL layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the depth of the concave portions is 12 nm to 180 nm;

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

[6] A method for manufacturing the organic light emitting diodeaccording to [5], the method including: preparing a substrate having astructure in which a plurality of concave portions corresponding to thetwo-dimensional lattice structure are periodically and two-dimensionallyordered on a surface; and sequentially laminating the cathodicconductive layer, the organic EL layer, and the anodic conductive layeron the structure.

[7] The method for manufacturing the organic light emitting diodeaccording to [6], further including: preparing the substrate using thetwo-dimensional lattice structure as a mold, wherein the mold is amaster mold that is manufactured according to a dry etching method usinga particle mono-layer film as an etching mask, or a metallicelectroformed mold or resin mold that is obtained by transfer of themaster mold.

[8] The method for manufacturing the organic light emitting diodeaccording to [6], wherein the substrate is prepared according to a dryetching method in which a particle mono-layer film is prepared on asurface, a metal selected from the group consisting of Cr, Ni, Fe, andCo is vacuum-deposited on the particle mono-layer film, a mesh-shapedmetallic deposition layer, which reaches a surface of an original plateof the substrate from a gap between particles of the particle mono-layerfilm, is formed, the particle mono-layer film is removed, and themesh-shaped metallic deposition layer is used as an etching mask.

[9] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Ag or an alloy containing 70% bymass or more of Ag are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of convexportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the height of the convex portions is 12 nm to 180 nm; A (λ=450,p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D (λ=700,p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G (λ=700,p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J (λ=450,p=110−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

[10] An organic light emitting diode in which at least a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of convexportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the height of the convex portions is 12 nm to 180 nm;

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

[11] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Al or an alloy containing 70% bymass or more of Al are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of concaveportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the depth of the concave portions is 12nm to 180 nm;

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

[12] An organic light emitting diode in which at least a cathodicconductive layer formed from Al or an alloy containing 70% by mass ormore of Al, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of concaveportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the depth of the concave portions is 12nm to 180 nm;

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

[13] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Al or an alloy containing 70% bymass or more of Al are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of convexportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the height of the convex portions is 12nm to 180 nm;

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

[14] An organic light emitting diode in which at least a cathodicconductive layer formed from Al or an alloy containing 70% by mass ormore of Al, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure, in which a plurality of convexportions are periodically and two-dimensionally ordered, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the height of the convex portions is 12nm to 180 nm;

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

[15] The organic light emitting diode according to [1], [5], [11], or[12], wherein the depth of the concave portions is 15 nm to 70 nm.

[16] The organic light emitting diode according to [1], [5], [11], or[12], wherein the shape of the concave portions is a shape obtained bytransfer of a truncated conical shape or a columnar shape on thesubstrate, and the depth is 15 nm to 70 nm. [17] The organic lightemitting diode according to [1], [5], [11], or [12], wherein the shapeof the concave portions is a shape obtained by transfer of a sinusoidalwave shape on the substrate, and the depth is 50 nm to 160 nm.

[18] The organic light emitting diode according to [1], [5], [11], or[12], wherein the shape of the concave portions is a shape obtained bytransfer of a conical shape on the substrate, and the depth is 60 nm to170 nm.

[19] The organic light emitting diode according to [9], [10], [13], or[14], wherein the shape of the convex portions is a truncated conicalshape or a columnar shape on the substrate, and the height is 15 nm to70 nm.

[20] The organic light emitting diode according to [9], [10], [13], or[14], wherein the shape of the convex portions is a sinusoidal waveshape on the substrate, and the height is 50 nm to 160 nm.

[21] The organic light emitting diode according to [9], [10], [13], or[14], wherein the shape of the convex portions is a conical shape on thesubstrate, and the height is 60 to 170 nm.

[22] An image display device including the organic light emitting diodeaccording to any one of [1], [5], and [9] to [14].

[23] An illuminating device including the organic light emitting diodeaccording to any one of [1], [5], and [9] to [14].

[24] A method for manufacturing the organic light emitting diodeaccording to [10], [11], or [14], the method including: preparing asubstrate having a structure in which a plurality of convex portionscorresponding to the two-dimensional lattice structure are periodicallyand two-dimensionally ordered on a surface; and sequentially laminatingthe anodic conductive layer, the organic EL layer, and the cathodicconductive layer on the structure.

[25] The method for manufacturing the organic light emitting diodeaccording to [24], wherein the substrate is prepared according to a dryetching method using a particle mono-layer film as an etching mask.

[26] The method for manufacturing the organic light emitting diodeaccording to [24], further including: preparing the substrate using thetwo-dimensional lattice structure as a mold, wherein the mold is amaster mold that is manufactured according to the dry etching methodusing the particle mono-layer film as the etching mask, or a metallicelectroformed mold or resin mold that is obtained by transfer of themaster mold.

[27] A method for manufacturing the organic light emitting diodeaccording to [9], [12], or [13], the method including: preparing asubstrate having a structure in which a plurality of concave portionscorresponding to the two-dimensional lattice structure are periodicallyand two-dimensionally ordered on a surface; and sequentially laminatingthe cathodic conductive layer, the organic EL layer, and the anodicconductive layer on the structure.

[28] The method for manufacturing the organic light emitting diodeaccording to [27], further including: preparing the substrate using thetwo-dimensional lattice structure as a mold, wherein the mold is amaster mold that is manufactured according to the dry etching methodusing the particle mono-layer film as the etching mask, or a metallicelectroformed mold or resin mold that is obtained by transfer of themaster mold.

[29] The method for manufacturing the organic light emitting diodeaccording to [27], wherein the substrate is prepared according to a dryetching method in which a particle mono-layer film is prepared on asurface, a metal selected from the group consisting of Cr, Ni, Fe, andCo is vacuum-deposited on the particle mono-layer film, a mesh-shapedmetallic deposition layer, which reaches a surface of an original plateof the substrate from a gap between particles of the particle mono-layerfilm, is formed, the particle mono-layer film is removed, and themesh-shaped metallic deposition layer is used as an etching mask.

In a case where the two-dimensional lattice structure is a squarelattice, it is preferable to make a correction by multiplying coordinatevalues of the distance p (nm) between the centers of the concaveportions or the distance p (nm) between the centers of the convexportions by (√3/2). That is, the invention includes the followingaspects.

[30] An organic light emitting diode in which at least an anodicconductive layer, an organic EL layer that includes a light emittinglayer containing an organic light emitting material, and a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of concave portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic EL layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the depth of the concave portions is 12 nm to 180 nm;

A (λ=450, p=(√3/2)(258+W(½))), B (λ=500, p=(√3/2)(319+W(½))), C (λ=600,p=(√3/2)(406+W(½))), D (λ=700, p=(√3/2)(484+W(½))), E (λ=800,p=(√3/2)(561+W(½))), F (λ=800, p=(√3/2)(493−W(½))), G (λ=700,p=(√3/2)(425−W(½))), H (λ=600, p=(√3/2)(353−W(½))), I (λ=500,p=(√3/2)(262−W(½))), and J (λ=450, p=(√3/2)(110−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[31] An organic light emitting diode in which at least a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag, an organic EL layer that includes a light emitting layercontaining an organic light emitting material, and an anodic conductivelayer are sequentially laminated on a substrate, and a two-dimensionallattice structure (square lattice structure), in which a plurality ofconcave portions are periodically and two-dimensionally ordered, isprovided on a surface of the cathodic conductive layer on an organic ELlayer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the depth of the concave portions is 12 nm to 180 nm;

A (λ=450, p=(√3/2)(258+W(½))), B (λ=500, p=(√3/2)(319+W(½))), C (λ=600,p=(√3/2)(406+W(½))), D (λ=700, p=(√3/2)(484+W(½))), E (λ=800,p=(√3/2)(561+W(½))), F (λ=800, p=(√3/2)(493−W(½))), G (λ=700,p=(√3/2)(425−W(½))), H (λ=600, p=(√3/2)(353−W(½))), I (λ=500,p=(√3/2)(262−W(½))), and J (λ=450, p=(√3/2)(110−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[32] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Ag or an alloy containing 70% bymass or more of Ag are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of convex portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side; wherein an extraction wavelengthλ (nm) of light from the organic light emitting diode and a distance p(nm) between centers of the convex portions in the two-dimensionallattice structure are within a region surrounded by straight linessequentially connecting the following coordinates A, B, C, D, E, F, G,H, I, J, and A in a graph illustrating a relationship between the lightextraction wavelength and the distance; and the height of the convexportions is 12 nm to 180 nml;

A (λ=450, p=(√3/2)(258+W(½))), B (λ=500, p=(√3/2)(319+W(½))), C (λ=600,p=(√3/2)(406+W(½))), D (λ=700, p=(√3/2)(484+W(½))), E (λ=800,p=(√3/2)(561+W(½))), F (λ=800, p=(√3/2)(493−W(½))), G (λ=700,p=(√3/2)(425−W(½))), H (λ=600, p=(√3/2)(353−W(½))), I (λ=500,p=(√3/2)(262−W(½))), and J (λ=450, p=(√3/2)(110−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[33] An organic light emitting diode in which at least a cathodicconductive layer formed from Ag or an alloy containing 70% by mass ormore of Ag, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of convex portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A, B, C, D, E, F, G, H, I, J, and A in a graph illustratinga relationship between the light extraction wavelength and the distance;and the height of the convex portions is 12 nm to 180 nm;

A (λ=450, p=(√3/2)(258+W(½))), B (λ=500, p=(√3/2)(319+W(½))), C (λ=600,p=(√3/2)(406+W(½))), D (λ=700, p=(√3/2)(484+W(½))), E (λ=800,p=(√3/2)(561+W(½))), F (λ=800, p=(√3/2)(493−W(½))), G (λ=700,p=(√3/2)(425−W(½))), H (λ=600, p=(√3/2)(353−W(½))), I (λ=500,p=(√3/2)(262−W(½))), and J (λ=450, p=(√3/2)(110−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[34] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Al or an alloy containing 70% bymass or more of Al are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of concave portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the depth of the concave portions is 12nm to 180 nm;

A′ (λ=300, p=(√3/2)(220+W(½))), B′ (λ=400, p=(√3/2)(295+W(½))), C′(λ=500, p=(√3/2)(368+W(½))), D′ (λ=600, p=(√3/2)(438+W(½))), E′ (λ=700,p=(√3/2)(508+W(½))), F′ (λ=800, p=(√3/2)(575+W(½))), G′ (λ=800,p=(√3/2)(505−W(½))), H′ (λ=700, p=(√3/2)(438−W(½))), I′ (λ=600,p=(√3/2)(368−W(½))), J′ (λ=500, p=(√3/2)(298−W(½))), K′ (λ=400,p=(√3/2)(225−W(½))), and L′ (λ=300, p=(√3/2)(150−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[35] An organic light emitting diode in which at least a cathodicconductive layer formed from Al or an alloy containing 70% by mass ormore of Al, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of concave portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the depth of the concave portions is 12nm to 180 nm;

A′ (λ=300, p=(√3/2)(220+W(½))), B′ (λ=400, p=(√3/2)(295+W(½))), C′(λ=500, p=(√3/2)(368+W(½))), D′ (λ=600, p=(√3/2)(438+W(½))), E′ (λ=700,p=(√3/2)(508+W(½))), F′ (λ=800, p=(√3/2)(575+W(½))), G′ (λ=800,p=(√3/2)(505−W(½))), H′ (λ=700, p=(√3/2)(438−W(½))), I′ (λ=600,p=(√3/2)(368−W(½))), J′ (λ=500, p=(√3/2)(298−W(½))), K′ (λ=400,p=(√3/2)(225−W(½))), and L′ (λ=300, p=(√3/2)(150−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[36] An organic light emitting diode in which at least an anodicconductive layer, an organic electroluminescence layer that includes alight emitting layer containing an organic light emitting material, anda cathodic conductive layer formed from Al or an alloy containing 70% bymass or more of Al are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of convex portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the height of the convex portions is 12nm to 180 nm;

A′ (λ=300, p=(√3/2)(220+W(½))), B′ (λ=400, p=(√3/2)(295+W(½))), C′(λ=500, p=(√3/2)(368+W(½))), D′ (λ=600, p=(√3/2)(438+W(½))), E′ (λ=700,p=(√3/2)(508+W(½))), F′ (λ=800, p=(√3/2)(575+W(½))), G′ (λ=800,p=(√3/2)(505−W(½))), H′ (λ=700, p=(√3/2)(438−W(½))), I′ (λ=600,p=(√3/2)(368−W(½))), J′ (λ=500, p=(√3/2)(298−W(½))), K′ (λ=400,p=(√3/2)(225−W(½))), and L′ (λ=300, p=(√3/2)(150−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

[37] An organic light emitting diode in which at least a cathodicconductive layer formed from Al or an alloy containing 70% by mass ormore of Al, an organic electroluminescence layer that includes a lightemitting layer containing an organic light emitting material, and ananodic conductive layer are sequentially laminated on a substrate, and atwo-dimensional lattice structure (square lattice structure), in which aplurality of convex portions are periodically and two-dimensionallyordered, is provided on a surface of the cathodic conductive layer on anorganic electroluminescence layer side;

wherein an extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the convexportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance; and the height of the convex portions is 12nm to 180 nm;

A′ (λ=300, p=(√3/2)(220+W(½))), B′ (λ=400, p=(√3/2)(295+W(½))), C′(λ=500, p=(√3/2)(368+W(½))), D′ (λ=600, p=(√3/2)(438+W(½))), E′ (λ=700,p=(√3/2)(508+W(½))), F′ (λ=800, p=(√3/2)(575+W(½))), G′ (λ=800,p=(√3/2)(505−W(½))), H′ (λ=700, p=(√3/2)(438−W(½))), I′ (λ=600,p=(√3/2)(368−W(½))), J′ (λ=500, p=(√3/2)(298−W(½))), K′ (λ=400,p=(√3/2)(225−W(½))), and L′ (λ=300, p=(√3/2)(150−W(½))), in which W(½)represents a half width at half maximum of a light emitting peak in aspectrum of the light emitting material that constitutes the lightemitting layer.

Effect of the Invention

According to the invention, an organic light emitting diode excellent inlight extraction efficiency, a method for manufacturing the same, and animage display device and an illuminating device that are provided withthe organic light emitting diode may be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an example of the structureof organic light emitting diodes of first and fifth aspects.

FIG. 2 is a graph in which an extraction wavelength λ (nm) of light froman organic light emitting diode is shown in the horizontal axis, and adistance p (nm) between the centers of concave portions or a distance p(nm) between the centers of convex portions in a two-dimensional latticestructure is shown in the vertical axis, and which illustrates arelationship between the extraction wavelength λ and the distance p inthe first to fourth aspects of the invention.

FIG. 3A is a schematic diagram of a surface of a cathodic conductivelayer on an organic EL layer side, which is used for calculation ofconversion efficiency from a surface plasmon to light.

FIG. 3B is a cross-sectional diagram of the cathodic conductive layer ofFIG. 3A.

FIG. 4A is a diagram illustrating a structure of a multi-layerdielectric substance, which is used to explain a method of obtaining anequivalent refractive index of a uniform dielectric substance in a casewhere the organic EL layer is constituted by two layers.

FIG. 4B is a diagram illustrating the structure of the multi-layerdielectric substance, which is used to explain the method of obtainingthe equivalent refractive index of the uniform dielectric substance in acase where the organic EL layer is constituted by three layers.

FIG. 4C is a diagram illustrating the structure of the multi-layerdielectric substance, which is used to explain the method of obtainingthe equivalent refractive index of the uniform dielectric substance in acase where the organic EL layer is constituted by four layers.

FIG. 5 is a schematic diagram illustrating an example of the structureof organic light emitting diodes of second and sixth aspects.

FIG. 6 is a side view of a substrate that is prepared in Example 1.

FIG. 7 is a graph that is created in Test Example 1.

FIG. 8 is a schematic diagram illustrating an example of the structureof organic light emitting diodes of third and seventh aspects.

FIG. 9 is a schematic diagram illustrating an example of the structureof organic light emitting diodes of fourth and eighth aspects.

FIG. 10 is a graph in which an extraction wavelength λ (nm) of lightfrom the organic light emitting diode is shown in the horizontal axis,and a distance p (nm) between the centers of concave portions or adistance p (nm) between the centers of convex portions in atwo-dimensional lattice structure is shown in the vertical axis, andwhich illustrates a relationship between the extraction wavelength λ andthe distance p in the fifth to eighth aspects of the invention.

FIG. 11 is a graph that is created in Test Example 3.

FIG. 12 is a perspective diagram illustrating an example of a cathodicconductive layer that includes concave portions having a truncatedconical shape on a surface on an organic EL layer side.

FIG. 13 is a perspective diagram illustrating an example of the cathodicconductive layer that includes convex portions having a truncatedconical shape on the surface of the organic EL layer side.

FIG. 14 is a perspective diagram illustrating an example of the cathodicconductive layer that includes concave portions having a sinusoidal waveshape on the surface of the organic EL layer side.

FIG. 15 is a perspective diagram illustrating an example of the cathodicconductive layer that includes convex portions having a sinusoidal waveshape on the surface of the organic EL layer side.

FIG. 16 is a perspective diagram illustrating an example of the cathodicconductive layer that includes columnar concave portions on the surfaceof the organic EL layer side.

FIG. 17 is a perspective diagram illustrating an example of the cathodicconductive layer that includes columnar convex portions on the surfaceof the organic EL layer side.

FIG. 18 is a perspective diagram illustrating an example of the cathodicconductive layer that includes conical concave portions on the surfaceof the organic EL layer side.

FIG. 19 is a perspective diagram illustrating an example of the cathodicconductive layer that includes conical convex portions on the surface ofthe organic EL layer side.

FIG. 20 is a diagram illustrating an example of the structure of theconvex portions having a sinusoidal wave shape of the invention.

FIG. 21 is a top view illustrating an example of arrangement of theconvex portions having a sinusoidal wave shape of the invention.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

<<Organic Light Emitting Diode of First Aspect>>

In an organic light emitting diode according to a first aspect of theinvention, at least an anodic conductive layer, an organic EL layerincluding a light emitting layer, and a cathodic conductive layer formedfrom Ag or an alloy containing 70% by mass or more of Ag aresequentially laminated on a substrate. A two-dimensional latticestructure, in which a plurality of concave portions are periodically andtwo-dimensionally ordered, is provided on a surface of the cathodicconductive layer on an organic EL layer side.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the concave portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A, B,C, D, E, F, G, H, I, J, and A in a graph illustrating a relationshipbetween the light extraction wavelength and the distance, and the depthof the concave portions is 15 nm to 70 nm.

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

Hereinafter, the organic light emitting diodes of the aspects will bedescribed with reference to the attached drawings.

FIG. 1 shows a partial schematic cross-sectional diagram illustrating aconfiguration according to an embodiment of the organic light emittingdiode of a first aspect of the invention.

The organic light emitting diode 10 of this embodiment is an organiclight emitting diode having a layer configuration of a type generallycalled a bottom emission type. In the organic light emitting diode 10,an anodic conductive layer 12 formed from a transparent conductor, anorganic EL layer 13, and a cathodic conductive layer 14 formed from Agor an alloy containing 70% by mass or more of Ag are sequentiallylaminated on a transparent substrate 11.

The organic EL layer 13 includes a hole implantation layer 13 a, a holetransport layer 13 b, a light emitting layer 13 c containing an organiclight emitting material, an electron transport layer 13 d, and anelectron implantation layer 13 e that are sequentially laminated fromthe side of the anodic conductive layer 12. In the layers, the functionof one layer may be one, or two or more. For example, the electrontransport layer and the light emitting layer may be realized by onelayer.

A voltage is applied to the anodic conductive layer 12 and the cathodicconductive layer 14.

In the organic light emitting diode 10, when a voltage may be applied tothe anodic conductive layer 12 and the cathodic conductive layer 14,holes and electrons are implanted to the organic EL layer 13 from theanodic conductive layer 12 and the cathodic conductive layer 14,respectively. The holes and electrons that are implanted are coupledwith each other in the light emitting layer 13 c, and thus excitons aregenerated. When the excitons are recoupled, light is generated.

A structure (two-dimensional lattice structure), in which a plurality ofconvex portions 15 are periodically and two-dimensionally ordered, isprovided on a surface of the substrate 11 on a side at which the anodicconductive layer 12 is laminated. When the anodic conductive layer 12,the organic EL layer 13 (the hole implantation layer 13 a, the holetransport layer 13 b, the light emitting layer 13 c, the electrontransport layer 13 d, and the electron implantation layer 13 e) aresequentially laminated on the structure, the same structure as thesurface of the substrate 11 is formed on surfaces of the respectivelayers on a cathodic conductive layer 14 side. Accordingly, when thecathodic conductive layer 14 is finally laminated on the organic ELlayer 13, a structure inverted from the structure of the surface of thesubstrate 11, that is, a two-dimensional lattice structure, in which aplurality of concave portions 16 are periodically and two-dimensionallyordered, is formed on a surface of the cathodic conductive layer 14 onan organic EL layer 13 side.

When the two-dimensional lattice structure is provided, a surfaceplasmon is converted into propagation light on a surface of the cathodicconductive layer 14.

When light emission occurs from light emitting molecules in the lightemitting layer 13 c, near-field light is generated at a very closeportion. Since a distance between the light emitting layer 13 c and thecathodic conductive layer 14 is very short, the near-field light isconverted into energy of a propagation type surface plasmon on a surfaceof the cathodic conductive layer 14.

The propagation-type surface plasmon on the metal surface representsthat a compression wave of free electrons occurred by an incidentelectromagnetic wave (near-field light or the like) is accompanied witha surface electromagnetic field. In a case of the surface plasmon thatis present on a flat metal surface, a dispersion curve of the surfaceplasmon and a dispersion straight line of light (spatial propagationlight) do not intersect each other, and thus energy of the surfaceplasmon may not be extracted as light. Conversely, when a latticestructure is formed in the metal surface, the dispersion curve of thespatial propagation light diffracted by the lattice structure intersectsthe dispersion curve of the surface plasmon, and thus the energy of thesurface plasmon may be extracted as radiant light.

As described above, when the two-dimensional lattice structure isprovided, energy of the light that has disappeared as the surfaceplasmon is extracted. The extracted energy is radiated from a surface ofthe cathodic conductive layer 14 as radiant light. At this time, thelight that is radiated from the cathodic conductive layer 14 is highlydirectional, and the majority thereof faces to an extraction surface.Accordingly, light with high intensity is emitted from the extractionsurface, and thus the extraction efficiency is improved.

Here, “periodically and two-dimensionally ordered” represents a state inwhich the plurality of concave portions 16 are periodically disposed inat least two directions on a plane. When being two-dimensionallyordered, the extraction efficiency is higher compared to a case ofone-dimension (a structure in which an arrangement direction is onedirection. For example, a plurality of grooves (or peaks) are disposedin parallel with each other).

Preferred specific examples of the two-dimensional lattice structureinclude a lattice structure in which the arrangement direction includestwo directions and an intersection angle thereof is 90° (squarelattice), a lattice structure in which the arrangement directionincludes three directions and an intersection angle thereof is 60°(triangular lattice (also, referred to as a hexagonal lattice)), and thelike, and the triangular lattice structure is particularly preferable.As the arrangement direction increases, conditions capable of obtainingdiffracted light increase, and thus the surface plasmon may be convertedinto propagation light with high efficiency.

A method of preparing the triangular lattice structure is notparticularly limited. However, for example, electron beam lithography,mechanical cutting, laser thermal lithography, interference exposure,more specifically, two-beam interference exposure and reductionexposure, an anodic oxidation method of alumina, a nano imprint methodfrom a master mold manufactured by the above-described methods, and thelike may be used. In a method in which a particle mono-layer film to bedescribed later is used, particles constituting the particle mono-layerfilm may be disposed in two-dimensional hexagonal closest packing, andthus when dry etching is carried out using the particle mono-layer filmas an etching mask, the triangular lattice structure may be convenientlyformed.

A method of preparing the square lattice structure is not particularlylimited. However, for example, electron beam lithography, mechanicalcutting, laser thermal lithography, interference exposure, morespecifically, two-beam interference exposure and reduction exposure, anano imprint method from a master mold manufactured by theabove-described methods, and the like may be used.

The shorter the distance from the surface of the cathodic metallic layeron a light emitting layer side to the light emitting layer is, thelarger a shift proportion of light emitting energy to the surfaceplasmon is. The invention functions in a relatively effective mannerwith respect to such a device.

The depth of the concave portions 16 is 12 nm to 180 nm, and morepreferably 15 nm to 70 nm.

When the depth is less than 12 nm or exceeds 180 nm, an improvementeffect of the light extraction efficiency is not sufficient.

The reason why the depth of the concave portions 16 is limited to theabove-described range is as follows. That is, when the depth of theconcave portions 16 is less than 12 nm, the diffraction wave of thesurface plasmon may not be sufficiently generated by the two-dimensionallattice structure, and thus the effect of extracting the surface plasmonas radiant light decreases. In addition, when the depth of the concaveportions 16 exceeds 180 nm, the surface plasmon starts to have localizedtype properties instead of the propagation type, and thus the extractionefficiency of the radiant light decreases. Furthermore, in a case wherethe depth of the concave portions 16 exceeds 180 nm, when sequentiallylaminating an anodic layer, an organic thin film layer, and a cathodiclayer of the organic light emitting diode, concavities and convexitiesbecome steep. Therefore, a possibility that the anode and the cathodeare short-circuited increases, and thus this range is not preferable.

The depth of the concave portions 16 is the same as the height of theconvex portions 15, and thus the height of the convex portions 15 may beindirectly determined by measurement using AFM (atomic forcemicroscope). Specifically, first, with regard to one site of randomlyselected region of 5 μm×5 μm in the two-dimensional lattice structure,an AFM image is obtained. Next, a line is drawn in a diagonal directionof the AFM image, and the height of the convex portions 15 that interestthe line is individually obtained. An average value of the height of theconvex portions 15 is obtained. This process is carried out in the samemanner with respect to total 25 sites of randomly selected regions of 5μm×5 μm, and an average value of the height of the convex portions 15 ateach of the regions is obtained. The average values of the 25 sites ofregions, which are obtained in this manner, are further averaged, andthe resultant average value is set as the height of the convex portions15.

A shape of the convex portions 15 is not particularly limited as long asthe effect of the invention is obtained, and examples of the shapeinclude a columnar shape, a conical shape, a truncated conical shape, asinusoidal wave shape, a hemispheric shape, an approximately hemisphericshape, an elliptical shape, shapes derived from the shapes, and thelike. Another aspect of the shape of the convex portions 15 includesshapes in which a cross-section along an axis is a rectangular shape, atriangular shape, a trapezoidal shape, a sinusoidal wave shape, asemicircular shape, an approximately semicircular shape, an ellipticalshape, shapes derived from the shapes, and the like. In addition,tangential lines between the convex portions 15 and a substrate surfacemay come into contact with each other, or may be separated from eachother as long as the effect of the invention is provided.

The light extraction efficiency from the surface plasmon variesaccording to the shape and the height of the convex portions.

In a case where the shape of the convex portions 15 is the truncatedconical shape, the height is preferably 12 nm to 180 nm, more preferably15 nm to 70 nm, and still more preferably 20 nm to 50 nm. The truncatedconical shape that is exemplified here represents a structure in whichthe upper bottom and the lower bottom have a circular shape, a diameterration thereof is within a range of 10/100 to 90/100, planes of theupper bottom and the lower bottom are parallel with each other, and eachgenerating line is a straight line. As a microstructure, fromarrangement in which two lower bottoms of two adjacent columns come intocontact with each other to arrangement in which the two lower bottomsare apart from each other by a distance of approximately five times thediameter of the lower bottoms are preferable.

In addition, in a case where the shape of the convex portions 15 is thesinusoidal wave shape, the height is preferably 12 nm to 180 nm, morepreferably 50 nm to 160 nm, and still more preferably 70 nm to 140 nm.Here, for example, when drawing a straight line connecting two adjacentpoints of lattice points a of hexagonal closest arrangement on a plane,and considering a sinusoidal wave in which a plane including thestraight line and the Z-axis is set as a vibrating surface, and whenassuming a sinusoidal wave of a wavelength in which each of therespective lattice points a has the maximum value, and an intermediatepoint β of the lattice points adjacent to each other has the minimumvalue, the sinusoidal wave shape represents a stereoscopic shape (FIG.20) that is constituted by a plane obtained by cutting the sinusoidalwave at a position β apart from arbitrary lattice point α by ±½wavelength and by rotating the cut sinusoidal wave about the Z-axispassing through the lattice point. When the stereoscopic shape 15′ isset as a constituent unit, FIG. 21 shows a top view of a structure inwhich a plurality of the constituent units are disposed in such a mannerthat the vertex α of the sinusoidal wave coincides with the latticepoint α of the hexagonal closest packing arrangement. In FIG. 21, aregion, which is located in the vicinity of the center of an equilateraltriangle constituted by three lattice points closest to each other andwhich is not coated with by a rotation plane, has the same height as thelowest height (the minimum value of the sinusoidal wave) of the rotationplane that is a top horizontal plane of the substrate 11.

In a case where the shape of the convex portions 15 is the conicalshape, the height is preferably 12 nm to 180 nm, more preferably 60 nmto 170 nm, and still more preferably 80 nm to 150 nm. Here, for example,the conical shape represents a structure in which the lower bottom has acircular shape and a generating line is a straight line. As amicrostructure, from arrangement in which two lower bottoms of twoadjacent columns come into contact with each other to arrangement inwhich the two lower bottoms are apart from each other by a distance ofapproximately five times the diameter of the lower bottoms arepreferable.

In addition, in a case where the shape of the convex portions 15 is acolumnar shape, the height is preferably 12 nm to 180 nm, morepreferably 15 nm to 70 nm, and still more preferably 20 nm to 50 nm.Here, for example, the columnar shape represents a structure in whichthe upper bottom and lower bottom have a circular shape, the diametersof the upper bottom and lower bottom are the same as each other, anupper bottom plane and a lower bottom plane are parallel with eachother, and a generating line is a straight line. As a microstructure,from an arrangement in which two lower bottoms of two adjacent columnscome into contact with each other to an arrangement in which the twolower bottoms are apart from each other by a distance of approximatelyfive times the diameter of the lower bottoms are preferable.

The truncated conical shape, the sinusoidal wave shape, the conicalshape, and the columnar shape represent typical shapes, and thestructure of the convex portions or concave portions of the invention isnot strictly limited to any of the above-described shapes as long as theeffect of the invention is provided. That is, shapes (approximateshapes) that are slightly deviated from the definition of the basicshapes are included in the scope of the invention as long as the effectof the invention is provided.

All of the structures of the truncated conical shape, the sinusoidalwave shape, the conical shape, and the columnar shape are given forexplanation of a convex type, but the effect of the invention may beobtained with respect to a concave type that is an inverted typethereof. The definition of the shape of the concave type structurerelates to a plane symmetry structure (mirror image) with a basal plane(a plane including the lowest portion of a plurality of structuralprotrusions) of the convex type surface structure set as a referenceplane (mirror plane). For example, when the plane symmetry structure isformed on a surface of a glass substrate, a space on a surface of thestructure on a reference plane side is a void, and a space on thesurface of the structure on a side opposite to the reference plane isconstituted by a glass material.

FIG. 12 shows a perspective diagram illustrating a surface of thecathodic conductive layer 14 on an organic EL layer side in a case ofusing the substrate 11 having a structure in which the plurality ofconvex portions are periodically and two-dimensionally ordered. FIG. 12shows an example in which a plurality of concave portions 16 having atruncated conical shape are periodically formed to be apart from eachother. The organic EL layer 13 (not shown) having a refractive index ncomes into contact with an upper side of the cathodic conductive layer14.

FIG. 13 shows an example in which a plurality of convex portions 116having a truncated conical shape are periodically formed to be apartfrom each other on a surface of the cathodic conductive layer 14 of athird aspect to be described later on an organic EL layer side. Theorganic EL layer 13 (not shown) having a refractive index n comes intocontact with an upper side of the cathodic conductive layer 14.

FIG. 14 shows a perspective diagram illustrating a surface of thecathodic conductive layer 14 on an organic EL layer side in a case ofusing the substrate 11 having a structure in which the plurality ofconvex portions are periodically and two-dimensionally ordered. FIG. 14shows an example in which a plurality of concave portions 16 a having asinusoidal wave shape are periodically formed. The organic EL layer 13(not shown) having a refractive index n comes into contact with an upperside of the cathodic conductive layer 14.

FIG. 15 shows an example in which a plurality of convex portions 116 ahaving a sinusoidal wave shape are periodically formed on a surface ofthe cathodic conductive layer 14 of a third aspect to be described lateron an organic EL layer side. The organic EL layer 13 (not shown) havinga refractive index n comes into contact with an upper side of thecathodic conductive layer 14.

FIG. 16 shows a perspective diagram illustrating a surface of thecathodic conductive layer 14 on an organic EL layer side in a case ofusing the substrate 11 having a structure in which the plurality ofconvex portions are periodically and two-dimensionally ordered. FIG. 16shows an example in which a plurality of concave portions 16 b having acolumnar shape are periodically formed to be apart from each other. Theorganic EL layer 13 (not shown) having a refractive index n comes intocontact with an upper side of the cathodic conductive layer 14.

FIG. 17 shows an example in which a plurality of convex portions 116 bhaving a columnar shape are periodically formed to be apart from eachother on a surface of the cathodic conductive layer 14 of a third aspectto be described later on an organic EL layer side. The organic EL layer13 (not shown) having a refractive index n comes into contact with anupper side of the cathodic conductive layer 14.

FIG. 18 shows a perspective diagram illustrating a surface of thecathodic conductive layer 14 on an organic EL layer side in a case ofusing the substrate 11 having a structure in which the plurality ofconvex portions are periodically and two-dimensionally ordered. FIG. 18shows an example in which a plurality of concave portions 16 c having aconical shape are periodically formed spaced apart from each other. Theorganic EL layer 13 (not shown) having a refractive index n comes intocontact with an upper side of the cathodic conductive layer 14.

FIG. 19 shows an example in which a plurality of convex portions 116 chaving a conical shape are periodically formed with spaced from eachother on a surface of the cathodic conductive layer 14 of a third aspectto be described later on an organic EL layer side. The organic EL layer13 (not shown) having a refractive index n comes into contact with anupper side of the cathodic conductive layer 14.

In the first aspect of the invention, an extraction wavelength λ (nm) oflight from the organic light emitting diode 10 and a distance p (nm)between centers of the concave portions 16 in the two-dimensionallattice structure are within a region surrounded by straight linessequentially connecting the following coordinates A, B, C, D, E, F, G,H, I, J, and A in a graph illustrating a relationship between the lightextraction wavelength and the distance. In addition, the depth of theconcave portions 16 is 12 nm to 180 nm, and preferably 15 nm to 70 nm.According to this, the light extraction efficiency is significantlyimproved.

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½))

W(½) represents a half width at half maximum of a light emitting peak ina spectrum of the light emitting material contained in the lightemitting layer 13 c. The half width at half maximum represents a halfvalue of a width (half width) when horizontally cutting the lightemitting peak at a position of a half height of the peak height.

The spectrum of the light emitting material is peculiar to the lightemitting material, and W(½) is determined depending on a light emittingmaterial that is used. In a case where a plurality of peaks appear in aspectrum of a single light emitting material, W(½) of the highest peakis measured.

The spectrum of the light emitting material is obtained by a visiblelight spectrophotometer or the like.

The distance p (nm) between the centers of the concave portions 16 isdetermined by the extraction wavelength λ (nm).

The extraction wavelength λ (nm) is a wavelength when extracting energyfrom the surface plasmon as radiant light, and most commonly, the λ (nm)is an emission peak wavelength of the light emitting material.

When a specific extraction wavelength is λ₁ [λ₁ is a specific valuewithin a range of 450 nm to 800 nm], the distance p between the centersof the concave portions 16 may take an arbitrary value corresponding toa coordinate of λ=λ₁ within the above-described region. For example, ina case where λ₁ is 600 nm, the distance p may take an arbitrary valuefrom [353−W(½)] nm to [406+W(½)] nm.

The distance p between the centers of the concave portions 16 is thesame as the distance between the centers of the convex portions 15 inthe two-dimensional lattice structure of the surface of the substrate11, and thus the distance p is indirectly obtained as a lattice constantof the two-dimensional lattice structure by measuring the distancebetween the centers of the convex portions 15 by a laser diffractionmethod. That is, when laser light passes through a lattice (diffractionlattice), a phenomenon (diffraction) in which light turns round occurs.The distance by which the diffracted light proceeds after being emittedfrom each point of the lattice until reaching one point at which ascreen is positioned is different in each case, and thus light beamshaving phases different from each other according to a proceedingdistance overlap on the screen. As a result, interference (intensifyingor weakening) occurs.

With regard to parameters that specify a gap of the lattice, thefollowing definition is used as a parameter Λ. In a case of a triangularlattice, the height of the smallest equilateral triangle formed bylattice points (vertexes) of concavities and convexities is set as Λ,and in a case of a square lattice, the distance (lattice constant)between the closest lattices is set as Λ.

When a parameter of the lattice is set as Λ, a wavelength of laser lightis set as λ_(x), and an angle made by incident light and diffractedlight is set as θ, a screen is illuminated brightly with light emittedfrom the lattice at an angle θ with which a mathematical expression of Λsin θ=nλ_(x) [n=0, ±1, ±2, . . . ] is satisfied.

At the angle θ, proceeding distances of diffracted light beams emittedfrom one convex portion and another adjacent convex portion arecorrectly different from each other by an integer (here, n) wavelength,and thus interference, which intensifies the light beams, occurs on thescreen. The lattice parameter Λ may be obtained by measuring θ using theabove-described properties. The distance between the centers of theconvex portions 15, that is, the distance p between the centers of theconcave portions 16 may be obtained from the lattice parameter Λ. Forexample, in a case of the square lattice, the lattice parameter Λ thatis calculated becomes the distance p between the centers of the concaveportions 16 as is, and in a case of a trigonal lattice (hexagonallattice), a value obtained by multiplying the lattice parameter Λ, whichis calculated, by 2/√3 becomes the distance p between the centers of theconcave portions 16.

A relationship between the extraction wavelength λ (nm) and the distancep (nm) between the centers of the concave portions 16 will be describedin more detail with reference to FIG. 2.

FIG. 2 is a graph in which the extraction wavelength λ (nm) is shown inthe horizontal axis, and the distance p (nm) between the centers of theconcave portions is shown in the vertical axis.

As shown in FIG. 2, the coordinates A, B, C, D, and E are coordinatesobtained by shifting p of coordinates (λ, p) of (450, 258), (500, 319),(600, 406), (700, 484), and (800, 561) in a positive direction by W(½),and the coordinates F, G, H, I, and J are coordinates obtained byshifting a distance p of coordinates (λ, p) of (800, 493), (700, 425),(600, 353), (500, 262), and (450, 110) in a negative direction by W(½).When the shift width exceed W(½), the light extraction efficiency isimproved, but the effect is greatly inferior to a case where the shiftwidth is within W(½).

The smaller the shift width is, the more preferable. It is preferablethat the shift width be ⅕ W, more preferably 1/10 W, and still morepreferably 0. That is, it is particularly preferable that the extractionwavelength λ (nm) and the distance p (nm) between the centers of theconcave portions 16 be within a region surrounded by straight linessequentially connecting coordinates (λ, p) of (450, 258), (500, 319),(600, 406), (700, 484), (800, 561), (800, 493), (700, 425), (600, 353),(500, 262), and (450, 110) in a graph illustrating the relationshipbetween the light extraction wavelength and the distance.

The coordinates of 10 points of A to J are obtained by calculatingconversion efficiency from the surface plasmon to light. In addition,practically, a significant improvement in the light extractionefficiency when the extraction wavelength and the distance are withinthe region surrounded by straight lines sequentially connecting thecoordinates of the 10 points was confirmed with regard to a case wherethe extraction wavelength λ is 625 nm or 565 nm in [Examples] to bedescribed later.

Hereinafter, a method of calculating the light conversion efficiencyfrom the surface plasmon to light, which is carried out to specify thecoordinates, will be described.

First, a structure of the organic light emitting diode 10 is modeled asshown in FIG. 3. FIG. 3A shows a perspective diagram of the cathodicconductive layer 14, and FIG. 3B shows a cross-sectional diagram of thecathodic conductive layer 14 in a case where a surface thereof on anorganic EL layer 13 side is set as an upper side.

In the model shown in FIGS. 3A and 3B, the cathodic conductive layer 14is formed from silver. The thickness of the cathodic conductive layer 14is semi-infinite, and also spreads infinitely in an xy direction. Theorganic EL layer 13 (not shown) having a semi-infinite thickness and arefractive index n comes into contact with the upper side of thecathodic conductive layer 14.

The concave portions 16 are formed on a surface of the cathodicconductive layer 14 on an organic EL layer 13 side. The concave portions16 are holes, each being constituted by three-stage concentric columns.The height of each of the concentric columns is d/3, and the depth ofthe concave portions 16 is d. The radii of the respective concentriccolumns are r1, r2, and r3 from the lower side of the concave portions16. As shown in FIG. 3A, the concave portions 16 are disposed in atriangular (hexagonal) lattice shape, and the gap between the centers ofthe concave portions 16 adjacent to each other is indicated as p.

A reflectance in a case where a monochromatic plane wave is verticallyincident to the structure from an organic EL layer side is calculatedusing a supercomputer. A method used for the calculation is a rigorouscoupled wave analysis (RCWA) method. The RCWA method is not a scalaranalysis method but a kind of differential method among rigorouselectromagnetic field analysis methods of a lattice structure inconsideration of the fact that an electric field and a magnetic fieldare vector fields. In this method, the diffraction lattice is expressedby Fourier-series development, a coupling equation with anelectromagnetic filed is obtained, and the coupling equation isnumerically solved under boundary conditions to calculate diffractionefficiency [with regard to the details of the RCWA method, refer to L.Li, “New formulation of the Fourier modal method for crossedsurface—relief gratings,” J. Opt. Soc. Am. A14, 2758-2767 (1997)].Accuracy of the calculation depends on a diffraction order that is putinto for the calculation, and the larger the diffraction order is, thehigher the accuracy becomes. However, calculation time and a memory arealso consumed. The diffraction order considered in the calculation is2601 orders (51 orders×51 orders). The reflectance is calculated byassuming the refractive index n of the organic EL layer as 1.6, 1.7, or1.8 and by systematically changing the distance p between the centers ofthe holes and depth d of the holes with respect to cases where awavelength (corresponding to the extraction wavelength λ) of themonochromatic plane wave is 450 nm, 500 nm, 600 nm, 700 nm, and 800 nm.

The lower the obtained reflectance is, the higher efficiency ofconversion of incident light into the surface plasmon becomes. Thisrepresents that from reciprocal theorem of Lorenz, the conversionefficiency from the surface plasmon to light is high at a portion havinga small reflectance.

In addition, among the above-described coordinates, coordinates at whichthe reflectance becomes the minimum value when the refractive index n is1.6 include coordinates (λ, P) of (450, 258), (500, 319), (600, 406),(700, 484), and (800, 561). In addition, coordinates at which thereflectance becomes the minimum value when the refractive index n is 1.8include coordinates (λ, P) of (450, 110), (500, 262), (600, 353), (700,425), and (800, 493). Coordinates at which the reflectance becomes theminimum value when the refractive index n is 1.7 are approximatelyintermediate values between the case where the refractive index n is 1.6and the case where the refractive index n is 1.8.

In the above-described calculation, the reason why the lower limit ofthe refractive index n of the organic EL layer is assumed to 1.6, andthe upper limit is assumed to 1.8 is that commonly, the refractive indexof the organic EL layer of the organic light emitting diode is within arange of 1.6 to 1.8.

In a case where the organic EL layer is constituted by multiple layers,the refractive index in the organic EL layer is not necessarilyconstant, but in the calculation of the conversion efficiency, thecalculation may be carried out by assuming that the organic EL layer issubstituted with a dielectric substance (uniform dielectric substance)having an uniform refractive index with which a wave number of thesurface plasmon becomes the same as that in the case of the multiplelayers. When the refractive indexes of the respective layers are withina range of 1.6 to 1.8, the respective layers may be substituted with auniform dielectric substance having the refractive index within a rangeof 1.6 to 1.8.

In addition, an equivalent refractive index of a uniform dielectricsubstance, with which the wave number of the surface plasmon in the casewhere the organic EL layer is constituted by multiple layers and thewave number of the surface plasmon in the case where the organic ELlayer is substituted with a uniform dielectric substance become the sameas each other, may be obtained in the following manner.

FIGS. 4A, 4B, and 4C show diagrams illustrating a structure of themulti-layer dielectric substance that is used for the calculation of theequivalent refractive index of the uniform dielectric substance.

FIGS. 4A, 4B, and 4C illustrate cases where the organic EL layer isconstituted by two layers, three layers, and four layers, respectively,and a gray portion represents the cathodic conductive layer.

First, an equivalent refractive index n_(eff) with respect to thesurface plasmon in an original system (actual multi-layer structure) isobtained. The equivalent refractive index n_(eff) is given by Expression(1) described below by using a wave number k_(sp) of the surface plasmonand a wave number k₀ of propagation light in vacuum.

[Mathematical Expression 1]

n _(eff) =k _(sp) /k ₀  (1)

The wave number k_(sp) of the surface plasmon is given as a pole of areflection coefficient of the system.

For example, a case where the dielectric substance is constituted by twolayers (total three layers including the cathodic conductive layer as amedium) as shown in FIG. 4A is adapted.

A reflection coefficient r₁₂₃ in a system shown in FIG. 4A is given byExpression (2) described below.

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Expression}\mspace{14mu} 2} \right\rbrack & \; \\{r_{123} = \frac{r_{12} + {r_{23}{\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}{1 + {r_{12}r_{23}{\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}} & (2)\end{matrix}$

Here, h_(i) represents the thickness of a medium i, and r_(ij)represents a reflection coefficient of p-polarized light at an interfacewith a medium j when viewed from the medium i side, and is given byExpression (3) described below.

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Expression}\mspace{14mu} 3} \right\rbrack & \; \\{r_{ij} = \frac{\frac{k_{zi}}{ɛ_{i}} - \frac{k_{zj}}{ɛ_{j}}}{\frac{k_{zi}}{ɛ_{i}} - \frac{k_{zj}}{ɛ_{j}}}} & (3)\end{matrix}$

∈_(i) represents a specific dielectric constant of the medium i and hasa relationship represented by Expression (4) described below with arefractive index n_(i) of the medium i.

k_(zi) represents a normal component of a wave number vector at themedium i, and satisfies a relationship shown by Expression (5) describedbelow.

[Mathematical Expression 4]

∈_(i) =n _(i) ²  (4)

[Mathematical Expression 5]

k _(zi) ² +k _(x) ²=∈_(i) k ₀ ²  (5)

Here, k_(x) represents a tangential component of a wave number vector,and has a value common in the respective layers.

The pole of the reflection coefficient is obtained using therelationships. More specifically, the pole is k_(x) satisfying anequation in which a denominator of the reflection coefficient r₁₂₃ isset to 0, and thus is a root of Expression (6) described below ratherthan Expression (2) described previously.

[Mathematical Expression 6]

1+r ₁₂ r ₂₃exp(2ik _(z2) h ₂)=0  (6)

A value of k_(x) that is the root becomes the wave number k_(sp) of thesurface plasmon. The equivalent refractive index n_(eff) is obtainedfrom the wave number k_(sp). Furthermore, the refractive index n_(a) ofthe uniform dielectric substance is obtained using Expression (7)described below.

$\begin{matrix}\left\lbrack {{Mathematical}\mspace{14mu} {Expression}\mspace{14mu} 7} \right\rbrack & \; \\{n_{eff}^{2} = \frac{n_{a}^{2}n_{3}^{2}}{n_{a}^{2} + n_{3}^{2}}} & (7)\end{matrix}$

In a case of four or more layers, the refractive index is also obtainedin the same manner.

For example, in a case of four layers (the organic EL layer isconstituted by three layers, and the cathodic conductive layer isconstituted by one layer) as shown in FIG. 4B, a reflection coefficientr₁₂₃₄ may be recursively obtained using the reflection coefficient r₁₂₃in the case of the three layers. Specifically, reflection coefficientr₁₂₃₄ may be obtained by Expression (8) described below using the r₁₂₃as r₂₃₄.

In a case of five layers as shown in FIG. 4C or a case of six or morelayers, the reflection coefficient is also obtained in the same manner.

$\begin{matrix}{\mspace{79mu} \left\lbrack {{Mathematical}\mspace{14mu} {Expression}\mspace{14mu} 8} \right\rbrack} & \; \\\begin{matrix}{r_{1234} = \frac{r_{12} + {r_{234}{\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}{1 + r_{12} + {r_{234}{\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}} \\{= \frac{r_{12} + \left\lbrack {1 + {r_{23}r_{34}{\exp \left( {2\; k_{z\; 3}h_{3}} \right)}}} \right\rbrack + {\left\lbrack {r_{23}r_{34}{\exp \left( {2\; \; k_{z\; 3}h_{3}} \right)}} \right\rbrack {\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}{1 + {r_{23}r_{34}{\exp \left( {2\; k_{z\; 3}h_{3}} \right)}} + {{r_{12}\left\lbrack {r_{23} + {r_{34}{\exp \left( {2\; k_{z\; 3}h_{3}} \right)}}} \right\rbrack}{\exp \left( {2\; k_{z\; 2}h_{2}} \right)}}}}\end{matrix} & (8)\end{matrix}$

In addition, as is described in a manufacturing method to be describedlater, in a case where the manufacturing of the organic light emittingdiode 10 is carried out by preparing the substrate 11 having a structurein which a plurality of convex portions corresponding to thetwo-dimensional lattice structure are periodically and two-dimensionallyordered on a surface, and by sequentially laminating the anodicconductive layer 12, the organic EL layer 13, and the cathodicconductive layer 14 on the structure, the two-dimensional latticestructure, which is formed on the surface of the cathodic conductivelayer 14 on an organic EL layer 13 side, corresponds to the structure ofthe surface of the substrate 11. That is, the distance p between thecenters of the concave portions 16 is equal to the distance between thecenters of the convex portions on the surface of the substrate 11, andthe depth of the concave portions 16 is equal to the height of theconvex portions. Accordingly, the distance p between the centers of theconcave portions 16 and the depth of the convex portions 16 in thetwo-dimensional lattice structure on the surface of the cathodicconductive layer 14 may be obtained by measuring the distance betweenthe centers of the convex portions 15 on the surface of the substrate11, and the height of the convex portions 15, respectively.

As described above, the distance p between the centers of the concaveportions 16 may be indirectly obtained by measuring the distance betweenthe centers of the convex portions 15 using a laser diffraction method.In addition, similarly, the depth of the concave portions 16 may beindirectly obtained by measuring the height of the convex portions 15using AFM.

Hereinafter, the respective layers that constitute the organic lightemitting diode 10 will be described in more detail.

[Substrate 11]

A transparent body through which visible light passes is used for thesubstrate 11 of this embodiment.

As a material constituting the substrate 11 may be an inorganicmaterial, an organic material, or a combination thereof. Examples of theinorganic material include various kinds of glass such as quartz glass,alkali-free glass, and super white glass, transparent inorganic mineralssuch as mica, and the like. Examples of the organic material includeresin films such as a cycloolefin-based film and a polyester-based film,fiber-reinforced plastic materials in which a microfiber such as acellulose nanofiber is mixed in the resin films, and the like.

Although different depending on uses, a material having a highvisible-light transmittance is generally used for the substrate 11. Inaddition, a material, which has a transmittance of 70% or more,preferably 80% or more, and more preferably 90% or more without applyingdeflection to a spectrum in a visible light range (a wavelength of 380nm to 800 nm), is used.

[Anodic Conductive Layer 12]

A transparent conductor through which visible light passes is used forthe anodic conductive layer 12 in this embodiment.

The transparent conductor constituting the anodic conductive layer 12 isnot particularly limited, and materials in the related art may be usedas the transparent conductive material. Examples of the transparentconductor include indium tin oxide (ITO), indium zinc oxide (IZO), zincoxide (ZnO), zinc tin oxide (ZTO), and the like.

The thickness of the anodic conductive layer 12 is commonly 50 nm to 500nm.

In addition, the thickness of the respective layers constituting theorganic light emitting diode 10 may be measured by a spectroscopicellipsometer, a contact-type step gauge, an AFM, and the like.

[Organic EL Layer 13]

In the invention, the organic EL layer (electroluminescence) layer is alayer including at least a light emitting layer containing an organiclight emitting material, and may be configured by only the lightemitting layer. However, the organic EL layer generally includes aseparate layer in addition to the light emitting layer. The separatelayer may be constituted by an organic material or an inorganic materialas long as the function of the light emitting layer does notdeteriorate.

In this embodiment, the organic EL layer 13 is constituted by fivelayers of the hole implantation layer 13 a, the hole transport layer 13b, the light emitting layer 13 c, the electron transport layer 13 d, andthe electron implantation layer 13 e. Among these layers, the lightemitting layer is the most important, and for example, the holeimplantation layer or the electron implantation layer may be omitteddepending on a layer configuration. In addition, the electron transportlayer may also serve as the light emitting layer. A material thatconstitutes these layers is not particularly limited, and materials inthe related art may be used.

Among the materials, an organic light emitting material is used as amaterial constituting the light emitting layer 13 c.

Examples of the organic light emitting material include pigmentcompounds such as Tris[1-phenylisoquinoline-C2,N] iridium (III)(Ir(piq)₃), 1,4-bis[4-(N,N-diphenylaminostyrylbenzene)] (DPAVB), andBis[2-(2-benzoxazolyl)phenolato] Zinc (II) (ZnPBO). In addition, amaterial that is obtained by doping a separate material (host material)with a fluorescent pigment compound or a phosphorescence emittingmaterial may be used. In this case, examples of the host materialinclude a hole transport material, an electron transport material, andthe like.

As materials constituting the hole implantation layer 13 a, the holetransport layer 13 b, and the electron transport layer 13 d, organicmaterials are generally used, respectively.

Examples of the material (hole implantation material) constituting thehole implantation layer 13 a include compounds such as4,4′,4″-tris(N,N-2-naphthylphenylamino)triphenylamine (2-TNATA).

Examples of the material (hole transport material) constituting the holetransport layer 13 b include aromatic amine compounds such asN,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPD),copper phthalocyanine (CuPc), andN,N′-Diphenyl-N,N′-di(m-tolyl)benzidine (TPD).

Examples of the material (electron transport material) constituting theelectron transport layer 13 d include oxadiol-based compounds such as2,5-Bis(1-naphthyl)-1,3,4-oxadiazole (BND), and2-(4-tert-Butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD), metalcomplex-based compounds such as Tris(8-quinolinolato)aluminum (Alq), andthe like.

The electron implantation layer 13 e is not requisite. However, when theelectron implantation layer 13 e is provided between the electrontransport layer 13 d and the cathodic conductive layer 14, a differencein a work function may be reduced, and thus migration of electrons fromthe cathodic conductive layer 14 to the electron transport layer 13 dbecomes easy.

However, when a magnesium alloy such as Mg/Ag=10/90 is used as thecathodic conductive layer 14, even when the electron implantation layer13 e is not provided, the electron implantation effect may be obtained.

As the material constituting the electron implantation layer 13 e,lithium fluoride (LiF) and the like may be used.

The total thickness of the organic EL layer 13 is commonly 30 to 500 nm.

[Cathodic Conductive Layer 14]

The cathodic conductive layer 14 is formed from Ag or an ally containing70% by mass or more of Ag.

Specific examples of the alloy containing 70% by mass or more of Aginclude magnesium alloys such as the above-described Mg/Ag=10/90.

The thickness of the cathodic conductive layer 14 is commonly 50 to3,000 nm.

<Method for Manufacturing Organic Light Emitting Diode 10>

The method for manufacturing the organic light emitting diode 10 is notparticularly limited. However, the organic light emitting diode 10 isappropriately manufactured by preparing the substrate 11 having astructure in which a plurality of convex portions corresponding to thetwo-dimensional lattice structure are periodically and two-dimensionallyordered on a surface, and by sequentially laminating the anodicconductive layer 12, the organic EL layer 13 (the hole implantationlayer 13 a, the hole transport layer 13 b, the light emitting layer 13c, the electron transport layer 13 d, and the electron implantationlayer 13 e), and the cathodic conductive layer 14 on the structure.

Examples of the method for manufacturing the substrate having astructure in which the plurality of convex portions corresponding to thetwo-dimensional lattice structure is periodically and two-dimensionallyordered include electron beam lithography, mechanical cutting, laserthermal lithography, interference exposure, more specifically, two-beaminterference exposure and reduction exposure, an anodic oxidation methodof alumina, a nano imprint method from a master mold manufactured by theabove-described methods, and the like. However, among the methods,methods other than the two-beam interference exposure and the laserthermal lithography are not suitable for manufacturing a periodiclattice structure in a large area, and thus have restrictions on an areain an industrial use aspect. In addition, the two-beam interferenceexposure may manufacture a substrate having a small area to a certaindegree. However, in a case of an large area in which a side length isseveral cm or more, the manufacturing is affected by various disturbancefactors such as vibration, wind, thermal expansion and shrinkage,fluctuation of air, and voltage variation with respect to the entiretyof optical setup, and thus it is very difficult to prepare a uniform,correct, and periodic lattice structure.

Therefore, in the invention, as the method for preparing the substrate,a dry etching method in which a particle mono-layer film is used as anetching mask is preferable. In this method, a mono-layer film ofparticles having a primary particle size equal to or less than aneffective wavelength of light emission color is prepared on a surface ofa base material using the principle of Langmuir-Blodgett method(hereinafter, also referred as “LB method”), and thus a two-dimensionalclosest packing lattice in which control of a gap between particles isperformed with high accuracy may be obtained. The method is disclosed indetail, for example, in Japanese Unexamined Patent Application, FirstPublication No. 2009-158478.

In the particle mono-layer film, since the particles are closely packedin two dimensions, when a surface of the original substrate isdry-etched using the particle mono-layer film as an etching mask, atwo-dimensional lattice structure having a triangular lattice (hexagonallattice) shape with high accuracy may be formed. A two-dimensionallattice structure, which is formed on the surface of the cathodicconductive layer 14 using the substrate having the above-describedtwo-dimensional lattice structure, is highly accurate. Accordingly, evenin a large area, a diffraction wave of the surface plasmon may beobtained with high efficiency, and thus the light extraction efficiencyis further improved. As a result, the organic light emitting diode 10with high luminance may be obtained.

More specifically, the substrate may be prepared by carrying out acoating process of coating a surface of the original substrate(substrate before forming the structure) of the substrate with aparticle mono-layer film, and a process (dry etching process) ofdry-etching the original plate of the substrate using the particlemono-layer film as an etching mask.

Hereinafter, the respective processes will be described in more detail.

{Coating Process}

The coating process may be carried out by performing a particlemono-layer film forming process of putting a liquid (lower-layerliquid), which develops particles on a liquid surface of a water tank,into the water tank, adding dropwise a dispersed solution in whichparticles are dispersed in a solvent to the liquid surface of thelower-layer liquid, and vaporizing the solvent to form a particlemono-layer film constituted by particles on the liquid surface; and atransition process of moving the particle mono-layer film onto thesubstrate.

In addition, here, description is made with respect to an example inwhich hydrophobic particles and a hydrophobic organic solvent areselected as the particles and the organic solvent, and a hydrophilicliquid is used as the lower-layer liquid, but hydrophilic particles anda hydrophilic organic solvent may be selected as the particles and theorganic solvent, and a hydrophobic liquid may be used as the lower-layerliquid.

[Particle Mono-Layer Film Forming Process]

In the particle mono-layer film forming process, first, particles havinga hydrophobic surface are added into a highly volatile solvent (forexample, chloroform, methanol, ethanol, methyl ethyl ketone, methylisobutyl ketone, hexane, or the like) to prepared a dispersed solution.Separately, a water tank (trough) is prepared, and water (hereinafter,may be referred to as “lower-layer water”) as a lower-layer liquid isput into the water tank (trough). Next, when the dispersed solution isadded dropwise onto a liquid surface of the lower-layer water, particlesin the dispersed solution are developed on the liquid surface of thelower-layer water due to a dispersion medium. Accordingly, when thesolvent that is a dispersion medium is vaporized, a mono-layer film inwhich the particles are closely packed in two-dimensions is formed.

A particle size of the particles that are used for formation of theparticle mono-layer film is set in consideration of a distance betweenthe centers of the convex portions 15 to be formed. When the particlesize of the particles that are used becomes a distance between thecenters of the convex portions 15 to be formed on the surface of thesubstrate 11, that is, a distance p between the centers of the concaveportions 16.

In addition, in the particles, it is preferable that a variationcoefficient (a value obtained by dividing standard deviation by anaverage value) of the particle size be 15% or less, more preferably 10%or less, and still more preferably 5% or less. As described above,particles in which the variation coefficient of a particle size is smalland a variation in the particle size is small are used, a defective siteat which particles are not present is not likely to occur in theparticle mono-layer film to be formed. Accordingly, a particlemono-layer film in which a deviation in arrangement is small may beformed. When the deviation in the arrangement of the particle mono-layerfilm is small, a deviation in arrangement in a two-dimensional latticestructure that is formed on a surface of the cathodic conductive layer14 ultimately decreases. The smaller the deviation in the arrangement inthe two-dimensional lattice structure, the more efficiently the surfaceplasmon is converted into light on the surface of the cathodicconductive layer 14, and thus is preferable.

Examples of a material of particles constituting the particle mono-layerfilm include metals such as Al, Au, Ti, Pt, Ag, Cu, Cr, Fe, Ni, and Si,metal oxides such as SiO₂, Al₂O₃, TiO₂, MgO₂, and CaO₂, organic polymerssuch as polystyrene and polymethylmetacrylate, semiconductor materials,inorganic polymer, and the like. These may be used alone or incombination of two or more kinds thereof.

When the material of the particles and dry etching conditions to bedescribed later are selected, the height or shape of the convex portionsto be formed, that is, the depth and shape of the concave portions 16may be adjusted.

In a case where water is used as the lower-layer liquid, it ispreferable that the surface of the particles have hydrophobicity. In acase where the surface of the particles has hydrophobicity, as describedabove, when the dispersed solution of particles is developed on theliquid surface of the lower-layer liquid of the water tank (trough) toform the particle mono-layer film, the particle mono-layer film may beeasily formed using water as the lower-layer liquid, and the particlemono-layer film may be easily moved onto a substrate surface.

Among particles exemplified above, particles of the organic polymer suchas polystyrene have a hydrophobic surface, and thus the particles may beused as is. However, with regard to the metal particles or metal oxideparticles, the particles may be used after the surface is treated usinga hydrophobizing agent to be relatively hydrophobic.

Examples of the hydrophobizing agent include a surfactant, alkoxysilane,and the like.

A method in which the surfactant is used as the hydrophobizing agent iseffective for hydrophobization of various materials, and is effectivefor a case where the particles are formed from a metal, a metal oxide,or the like.

As the surfactant, cationic surfactants such ashexadecyltrimethylammonium bromide and decyltrimethylammonium bromide,and anionic surfactants such as sodium dodecyl sulfate, sodium4-octylbenzene sulfonate may be appropriately used. In addition,alkanethiol, a disulfide compound, tetradecanoic acid, and octadecanoicacid may be used.

The hydrophobization treatment using the surfactant may be carried outin a liquid after dispersing the particles in the liquid such as anorganic solvent and water, or may be carried out with respect toparticles in a dried state.

In the case of carrying out the hydrophobization treatment in theliquid, particle to be hydrophobized are added to and diffused in avolatile organic solvent composed of one or more kinds selected fromchloroform, methanol, ethanol, isopropanol, acetone, methyl ethylketone, ethyl ethyl ketone, toluene, n-hexane, cyclohexane, ethylacetate, and butyl acetate, and then a surfactant may further mixed tothe resultant mixture to further carry out the dispersion. As describedabove, when the particles are dispersed in advance, and then thesurfactant is added, the surface may be further uniformly hydrophobized.The dispersed solution after the hydrophobization treatment may be usedas is as a dispersed solution that is added dropwise to the liquidsurface of the lower-layer water.

In a case where the particles to be hydrophobized is in a state of anaqueous dispersion, the following method is also effective. In themethod, a surfactant is added to the aqueous dispersion to carry out thehydrophobization treatment of a particle surface in a water phase, andthen an organic solvent is added to the resultant material to performoil-phase extraction of the particle after being subjected to thehydrophobization treatment. The dispersed solution (dispersed solutionin which particles are dispersed in an organic solvent) that is obtainedin this manner may be used as is as a dispersed solution that is addeddropwise to the liquid surface of the lower-layer water.

In addition, to raise particle dispersion properties of the dispersedsolution, it is preferable to appropriately select and combine a kind oforganic solvent and a kind of surfactant. When the dispersed solutionhaving high particle dispersion properties is used, agglomeration of theparticles into a cluster shape is suppressed, and thus a particlemono-layer film in which the respective particles are closely packed intwo dimensions with high accuracy may be obtained in a relatively easymanner. For example, in a case of selecting chloroform as the organicsolvent, it is preferable to use decyltrimethylammonium bromide as thesurfactant. In addition to this, a combination of ethanol and sodiumdodecyl sulfate, a combination of methanol and sodium 4-octylbenzenesulfonate, a combination of methyl ethyl ketone and octadecanoic acid,and the like may be preferably exemplified.

With regard to a ratio between the particles to be hydrophobized and thesurfactant, it is preferable that the mass of the surfactant be ⅓ to1/15 times the mass of the particles to be hydrophobized.

In addition, during the hydropobization treatment, it is effective thatthe dispersed solution is stirred or the dispersed solution isirradiated with ultrasonic waves from the viewpoint of improvement ofthe particle dispersion properties.

A method in which alkoxysilane is used as the hydrophobizing agent iseffective during hydrophobization of particles of Si, Fe, Al, and thelike, or oxide particles of SiO₂, Al₂O₃, TiO₂, and the like. However,the method is not limited to the particles, and the method is applicableto any particle as long as the particle basically has a hydroxyl groupor the like on a surface thereof.

Examples of alkoxysilane include monomethyltrimethoxysilane,monomethyltriethoxysilane, dimethyldiethoxysilane,phenyltriethoxysilane, hexyltrimethoxysilane, decyltrimethoxysilane,vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane,2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,3-glycidoxypropyltrimethoxysilane,3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane,p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropylmethyldiethoxysilane,3-methacryloxypropyltriethoxysilane, 3-acryloxytrimethoxysilane,N-2(aminoethyl)3-aminopropylmethyldimethoxysilane,N-2(aminoethyl)3-aminopropyltrimethoxysilane,N-2(aminoethyl)3-aminopropyltriethoxysilane,3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,N-phenyl-3-aminopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane,3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane, andthe like.

In a case of using alkoxysilane as the hydrophobizing agent, thehydrophobization is carried out in such a manner that an alkoxysilylgroup in the alkoxysilane is hydrolyzed to a silanol group, and thesilanol group is dehydrated and condensed to a hydroxyl group on aparticle surface. Accordingly, it is preferable to carry out thehydrophobization using alkoxysilane in water.

In a case of carrying out the hydrophobization in water, for example, itis preferable to use a dispersant such as a surfactant in combination tostabilize a dispersed state of the particles before thehydrophobization. However, an hydrophobization effect of alkoxysilanemay be reduced depending on a kind of dispersant, and thus a combinationof the dispersant and the alkoxysilane is appropriately selected.

As a specific method of carrying out the hydrophobization usingalkoxysilane, first, particles are dispersed in water, an aqueousalkoxysilane-containing solution (aqueous solution containing ahydrolysate of alkoxysilane) is mixed to the dispersed solution, andthese are allowed to react with each other for a predetermined time, andpreferably 6 to 12 hours while being appropriately stirred in a range offrom room temperature to 40° C. When the reaction is allowed to occurunder these conditions, the reaction appropriately proceeds, and thus adispersed solution of sufficiently hydrophobized particles may beobtained. When the reaction excessively proceeds, silanol groups reactwith each other, and thus particles are coupled to each other.Therefore, the particle dispersion properties of the dispersed solutiondecreases, and there is a tendency for the particle mono-layer film thatis obtained to be constituted by two or more layers partiallyagglomerated into a cluster shape. On the other hand, when the reactionis not sufficient, the hydrophobization of the particle surface is alsonot sufficient. As a result, in the particle mono-layer film, there is atendency for a pitch between particles that are obtained to broaden.

In addition, alkoxysilane other than amine-based alkoxysilane ishydrolyzed under acid or alkali conditions, and thus it is necessary toadjust the pH of the dispersed solution to acidity or alkalinity duringreaction. The pH adjustment method is not limited. However, according toa method in which an aqueous acetic acid solution having a concentrationof 0.1 to 2.0% by mass, in addition to promotion of hydrolysis, aneffect of stabilizing the silanol group may be also obtained, and thusthis method is preferable.

With regard to a ratio between the particles to be hydrophobized and thealkoxysilane, it is preferable that the mass of the alkoxysilane be 1/10to 1/100 times the mass of the particles to be hydrophobized.

After reaction for a predetermined time, one or more kinds of theabove-described volatile organic solvents are added to the dispersedsolution to perform oil-phase extraction of the particles that arehydrophobized in water. At this time, the volume of the organic solventthat is added is preferably 0.3 to 3 times that of the dispersionsolution before addition of the organic solvent. The dispersed solution(dispersed solution in which particles are dispersed in an organicsolvent) that is obtained in this manner may be used as is as adispersed solution that is added dropwise to the liquid surface of thelower-layer water during a dropwise adding process. In addition, in thehydrophobization treatment, it is preferable to carry out stirring,irradiation of ultrasonic wave, and the like to increase the particledispersion properties of the dispersed solution during the treatment.When the particle dispersion properties of the dispersed solutionincreases, agglomeration of the particles into a cluster shape may besuppressed. Accordingly, a particle mono-layer film in which therespective particles are closely packed in two dimensions may beobtained in a relatively easy manner.

It is preferable that a concentration of particles in the dispersedsolution be set to 1 to 10% by mass. In addition, it is preferable thata dropwise addition rate be set to 0.001 to 0.01 ml/second. When theconcentration of particles in the dispersed solution and an amount ofdropwise addition are within the ranges, a tendency in which theparticles are partially agglomerated into a cluster shape and thus theparticles are constituted by two or more layers, a tendency in whichdefective sites at which the particles are not present occur, a tendencyin which a pitch between the particles broadens, and the like aresuppressed. Accordingly, a particle mono-layer film in which therespective particles are closely packed in two dimensions with highaccuracy may be obtained in a relatively easy manner.

It is preferable that the process of forming the particle mono-layerfilm be carried out under ultrasonic irradiation conditions. When theprocess of forming the particle mono-layer film is carried out whileemitting ultrasonic waves toward the water surface from the lower-layerwater, closest packing of the particle is promoted. Accordingly, aparticle mono-layer film, in which the respective particles are closelypacked in two dimensions with relatively high accuracy, may be obtained.

At this time, it is preferable that an output of the ultrasonic waves be1 to 1,200 W, and more preferably 50 to 600 W.

In addition, a frequency of the ultrasonic waves is not particularlylimited. However, for example, 28 kHz to 5 MHz is preferable, and 700kHz to 2 MHz is more preferable. Generally, when the frequency ofvibration is too high, energy absorption of water molecules begins tostart, and thus a phenomenon in which water vapor or water droplets riseup from a water surface occurs. Therefore, this range is not appropriatefor the LB method of the invention. In addition, generally, when thefrequency of vibration is too low, a cavitation radius in lower-layerwater increases, and thus bubbles are generated in water and emergestoward the water surface. When the bubbles are collected under theparticle mono-layer film, flatness of the water surface disappears, andthus this is not appropriate for carrying out the invention. Inaddition, a stationary wave is generated on the water surface due to theirradiation of ultrasonic waves. When an output is too high at anyfrequency, or the wave height of the water surface is too high accordingto tuning conditions of an ultrasonic vibrator and a transmitter, theparticle mono-layer film may be broken due to surface waves.

As described above, when the frequency of the ultrasonic waves isappropriately set, the closest packing of the particles may beeffectively promoted without breaking the particle mono-layer film thatis formed. However, for example, when the particles are composed ofsmall particles having a particle size of 100 nm or less, an acousticnatural frequency of vibration of the particles becomes very high, andthus it is difficult to apply the same ultrasonic vibration as acalculation result.

In this case, when calculation is carried out by assuming that naturalvibration corresponding to the mass to a degree of a dimer, a trimer, .. . an eicosamer of particles is applied, a necessary frequency ofvibration may be reduced to a practical range. Even when ultrasonicvibration corresponding to a natural frequency of vibration of anassembly of particles is applied, an effect of improving a packing ratioof particles is shown. An irradiation time of ultrasonic waves may besufficiently set in order for rearrangement of particles to becompleted, and the necessary time may vary depending on a particle size,a frequency of ultrasonic waves, a water temperature, and the like.However, it is preferable to carry out the irradiation of ultrasonicwaves for 10 seconds to 60 minutes under common preparation conditions,and more preferably for 3 minutes to 30 minutes.

Advantages that may be obtained by the irradiation of ultrasonic wavesinclude an effect of breaking a soft agglomerate of the particle, whichis easily generated during preparation of the dispersed solution, and aneffect of recovering a point defect, a line defect, crystal transition,and the like, which are generated once, to a certain degree in additionto the closest packing (random arrangement is converted into hexagonalclosest packing) of the particles.

The formation of the above-described particle mono-layer film isobtained by self-assembly of the particles. The principle is as follows.When the particles are collected, surface tension operates due to adispersion medium that is present between the particles. As a result,the particles are not randomly present, and automatically form atwo-dimensional closest packed structure. The closest packing due to thesurface tension is also referred to as arrangement by a horizontalcapillary force.

Particularly, for example, three particles, which have a spherical shapeand high particle size uniformity like colloidal silica, are collectedand come into contact with each other in a state of remaining on a watersurface, surface tension operates in such a manner that the total lengthof a water line of a particle group becomes the minimum, and thus thethree particles are stabilized with arrangement that is based on anequilateral triangle. In a case where the water line is located at thevertex of the particle group, that is, the particles get into theunderside of the liquid surface, the self-assembly does not occur, andthe particle mono-layer film is not formed. Accordingly, with regard tothe particles and the lower-layer water, when one side hashydrophobicity, it is important that the other side is set to havehydrophilicity in order for the particle group not to get into theunderside of the liquid surface.

As the lower-layer liquid, it is preferable to use water as describedabove. When water is used, relatively large surface free energyoperates, and thus there is a tendency that the closest packingarrangement, which is formed at once, of the particles may stably last.

[Transition Process]

In the transition process, the particle mono-layer film, which is formedon the liquid surface of the lower-layer water by the process of formingthe particle mono-layer film, is moved in a mono layer state onto theoriginal substrate that is an object to be etched.

A specific method of moving the particle mono-layer film onto theoriginal substrate is not particularly limited. Examples thereof includea method in which a hydrophobic original plate of a substrate is allowedto descend from the upper side while maintaining the hydrophobicoriginal plate in a state of being approximately parallel with aparticle mono-layer film so as to come into contact with the particlemono-layer film, and the particle mono-layer film is moved onto theoriginal substrate using affinity between the particle mono-layer filmand the substrate that have hydrophobicity; a method in which theoriginal substrate is disposed in advance within the lower-layer waterin the water tank in an approximately horizontal direction beforeforming the particle mono-layer film, the particle mono-layer film isformed on the liquid surface, and the liquid surface is allowed togradually descend to move the particle mono-layer film onto the originalsubstrate; and the like. According to the methods, the particlemono-layer film may be moved onto the substrate without using aparticular apparatus. However, from the viewpoint that even when theparticle mono-layer film has a relatively large area, the particlemono-layer film is easily moved onto the original substrate whilemaintaining the two-dimensional closest packing state, a so-called LBtrough method is preferably adapted.

In the LB trough method, the original substrate is immersed in thelower-layer water inside the water tank in advance in an approximatelyvertical direction, and in this state, the above-described process offorming the particle mono-layer film is carried out to form the particlemono-layer film. In addition, after the process of forming the particlemono-layer film, the original substrate is pulled toward the upper sideto move the particle mono-layer film onto the original substrate.

At this time, since the particle mono-layer film has been already formedin a mono-layer state on the liquid surface by the process of formingthe particle mono-layer film, even when the temperature condition (thetemperature of the lower-layer water) in the transition process, thepulling velocity of the original substrate, and the like vary slightly,there is no concern the particle mono-layer film collapses into multiplelayers, or the like.

Commonly, the temperature of the lower-layer water depends on anenvironmental temperature that varies according to a season or weather,and is approximately 10° C. to 30° C.

In addition, at this time, as the water tank, when using an LB troughapparatus provided with a surface-pressure sensor that measures asurface pressure of the particle mono-layer film based on the principleof Wilhelmy plate or the like, and a movable barrier that compresses theparticle mono-layer film in a direction along the liquid surface, it ispossible to move the particle mono-layer film having a relatively largearea onto the original substrate in a relatively stable manner.According to the apparatus, it is possible to compress the particlemono-layer film at a preferred diffusion pressure (density) whilemeasuring the surface pressure of the particle mono-layer film. Inaddition, the particle mono-layer film may be moved toward the originalsubstrate at a constant velocity. Accordingly, the transition of theparticle mono-layer film from the liquid surface to the originalsubstrate smoothly proceeds, and thus a trouble that the movement ofonly a particle mono-layer film with a small area onto the originalsubstrate is allowed, or the like is not likely to occur.

It is preferable that the diffusion pressure be 5 to 80 mNm⁻¹, and morepreferably 10 to 40 mNm⁻¹. With this diffusion pressure, a particlemono-layer film in which the respective particles are closely packed intwo dimensions with relatively high accuracy may be easily obtained. Inaddition, the pulling velocity of the original substrate is preferably0.5 to 20 mm/minute.

According to the transition process, the surface of the originalsubstrate may be coated with the particle mono-layer film.

Furthermore, after the transition process, a fixing process of fixingthe particle mono-layer film onto the original substrate may be carriedout as necessary. When the particle mono-layer film is fixed onto theoriginal substrate, a possibility that the particle moves on theoriginal substrate during the subsequent dry etching is suppressed, andthus the surface of the original substrate may be etched with highaccuracy in a relatively stable manner. Particularly, when the dryetching proceeds, the diameter of the particles gradually decreases, andthus the possibility that the particles moves on the original substrateincreases.

Examples of a method of the fixing process include a method using abinder and a sintering method.

In the method using a binder, a binder solution is supplied to the sideof particle mono-layer film of the original substrate on which theparticle mono-layer film so as to penetrate into between the particlemono-layer film and the original substrate.

A used amount of the binder is preferably 0.001 to 0.02 times the massof the particle mono-layer film. When the used amount of the binder iswithin the range, the particles may be sufficiently fixed withoutcausing a problem that due to an excessive amount of the binder, thebinder is filled up between particles, and thus accuracy of the particlemono-layer film is adversely affected. In a case where too much of thebinder solution is supplied, after penetration of the binder solution, asurplus portion of the binder solution may be removed by using a spincoater or by inclining the substrate.

As a kind of binder, alkoxysilane that is previously exemplified as thehydrophobizing agent, a general organic binder, an inorganic binder, andthe like may be used, and after the penetration of the binder solution,an appropriate heating treatment may be performed according to the kindof binder. In a case of using alkoxysilane as the binder, it ispreferable to carry out the heating treatment under conditions of 40° C.to 80° C. and 3 to 60 minutes.

In the case of adapting the sintering method, the original substrate onwhich the particle mono-layer film is formed may be heated to fuse therespective particles constituting the particle mono-layer film onto thesubstrate. The heating temperature may be determined according to amaterial of the particles and a material of the substrate. However, inparticles having a particle size of 1 μm or less, since an interfacereaction initiates at a temperature lower than the intrinsic meltingpoint of the material, the sintering is completed at a relatively lowertemperature. When the heating temperature is too high, a fusion area ofthe particles increases, and as a result, there is a possibility thataccuracy is affected by the increased fusion area, for example, theshape of the particle mono-layer film varies. In addition, when theheating is carried out in the air, the substrate or the respectiveparticle may be oxidized, and thus the heating is preferably carried outin an inert gas atmosphere. In a case where the sintering is carried outin an oxygen-containing atmosphere, it is necessary to set conditions inconsideration of an oxidation layer in an etching process to bedescribed later.

In the particle mono-layer film that is obtained as described above, adeviation D (%) in arrangement of the particles, which is defined byExpression (9) described below, is preferably 10% or less.

[Mathematical Expression 9]

D(%)=|B−A|×100/A  (9)

[in Expression (9), A represents an average particle size of theparticles, and B represents an average pitch between the particles inthe particle mono-layer film.]

In Expression (9), the “average particle size of the particles” of Arepresents an average primary particle size of the particlesconstituting the particle mono-layer film, and may be obtained by ausual method from a peak obtained by fitting a particle sizedistribution obtained by a particle dynamic scattering method to a Gausscurve.

The “pitch between particles” of B is a distance between vertexes of twoadjacent particles, and the “average pitch” is an average value in theparticle mono-layer film. In addition, the particles have a sphericalshape, the distance between vertexes of the two adjacent particles isthe same as a distance between the centers of the adjacent particles.

The average pitch between particles in the particle mono-layer film maybe obtained by AFM in the same manner as the distance p between thecenters of the convex portions 15.

In the particle mono-layer film in which the deviation D in thearrangement of the particles is 10% or less, the respective particlesare closely packed in two dimensions, and the gap between the particlesis controlled. Accordingly, accuracy of the arrangement is high.

{Dry Etching Process}

As described above, the substrate surface coated with the particlemono-layer film is dry-etched, and accordingly, a substrate having astructure in which a plurality of convex portions are periodically andtwo-dimensionally ordered may be obtained.

Specifically, when the dry etching is initiated, first, an etching gaspasses through a gap between the respective particles constituting theparticle mono-layer film, and reaches the surface of the originalsubstrate. Accordingly, concave portions are formed at the surfaceportion, and convex portions appear at portions corresponding to therespective particles, respectively. When the dry etching continues, theparticles on the respective convex portions are gradually etched, andthe size of the particles decreases. At the same time, the concaveportions on the surface of the original substrate become deep. Inaddition, finally, the respective particles are removed by the dryetching, and along with this, a structure in which the plurality ofconvex portions are periodically and two-dimensionally ordered is formedon the surface of the original substrate.

At this time, the height or shape of the convex portions that are formedmay be adjusted by adjusting dry etching conditions (bias, a gas flowrate, a kind of the deposition gas and an amount thereof, and the like).

Examples of the etching gas that is used for the dry etching include Ar,SF₆, F₂, CF₄, C₄F₈, C₅F₈, C₂F₆, C₃F₆, C₄F₆, CHF₃, CH₂F₂, CH₃F, C₃F₈,Cl₂, CCl₄, SiCl₄, BCl₂, BCl₃, BC₂, Br₂, Br₃, HBr, CBrF₃, HCl, CH₄, NH₃,O₂, H₂, N₂, CO, CO₂, and the like. The etching gas is not limited to thegases as long as the effect of the invention does not deteriorate. Amongthese gases, one or more kinds may be used according to the particlesconstituting the particle mono-layer film, the material of thesubstrate, and the like.

Examples of an etching apparatus that may be used include a reactive ionetching apparatus, an ion beam etching apparatus, and the like that arecapable of realizing anisotropic etching, and there is no particularlimitation to specifications such as a type of plasma generation, astructure of an electrode, a structure of a chamber, and a frequency ofhigh-frequency power source, as long as a bias electric field as smallas approximately 20 W may occur.

In the invention, it is preferable to set respective etching conditions(the material of the particles constituting the particle mono-layerfilm, the material of the substrate, a kind of etching gas, a biaspower, antenna power, a flow rate and a pressure of the gas, etchingtime, and the like) in such a manner that an etching selectivity (anetching rate of the substrate/an etching rate of the particle mono-layerfilm) in the dry etching process becomes 1.0 or less.

For example, in a case where colloidal silica particles are selected asparticles constituting a particle mono-layer film etching mask, a quartzsubstrate is selected as the substrate, and these are used incombination, when a gas such as Ar and CF₄ is used as the etching gas,etching may be carried out with a relatively low ratio between amplitudeand pitch.

In addition, when the bias of an electric field is set from tens of W toseveral hundreds of W, electrostatic particles in the etching gas, whichenter a plasma state, are accelerated and are incident to the substrateat a high speed in a direction that is approximately orthogonal to thesubstrate. Accordingly, when a gas having reactivity with respect to thesubstrate is used, a reaction velocity of vertical physicochemicaletching may be raised.

Although depending on the combination of the material of the substrateand the kind of etching gas, in the dry etching, isotropic etching dueto radicals generated by plasma occur concurrently. The etching by theradicals is chemical etching, and etching is isotropically carried outin all directions of an object to be etched. The radicals do not have acharge, and thus the etching rate is not controlled through setting ofthe bias power, and is managed by a concentration of the etching gas ina chamber. It is necessary to maintain a gas pressure to a certaindegree so as to carry out anisotropic etching by charged particles, andthus it is difficult to totally remove the influence of the radicals aslong as the reactive gas is used. However, a method of making a reactionvelocity slow by cooling a base material has been widely used, and anumber of apparatuses provided with the mechanism are available.Accordingly, it is preferable to use this method.

In addition, in the dry etching process, when the bias power is mainlyadjusted, and a so-called deposition gas is used in combinationaccording to circumstances, it is possible to form a two-dimensionallattice structure in which a ratio between the distance between thecenters of convex portions and the height (distance between thecenters/height) is relatively low in the substrate surface.

With regard to the structure that is formed in the substrate surface asdescribed above, when a distance C between the centers of the convexportions is obtained in the same manner as the method of obtaining theaverage pitch B between the particles in the particle mono-layer film asdescribed previously, the distance C is substantially the same as theaverage pitch B of the particle mono-layer film that is used. Inaddition, with regard to the structure, a deviation D′ (%) inarrangement that is defined in Expression (10) described below isobtained, the resultant value is also substantially the same as thedeviation D in arrangement in the particle mono-layer film that is used.

[Mathematical Expression 10]

D′(%)=|C−A|×100/A  (10)

[in Expression (10), A represents an average particle size of theparticles constituting the particle mono-layer film that is used, and Crepresents the distance between the centers of the convex portions.]

In addition, in a case of preparing a substrate having a structure inwhich a plurality of concave portions are periodically andtwo-dimensionally ordered by the dry etching method, a method in which ametallic mesh mask prepared using the particle mono-layer film is usedmay be exemplified. That is, the particle mono-layer film is prepared ona surface of the original substrate, a metal such as Cr, Ni, Fe, and Cois vacuum-deposited from an upper side of the particle mono-layer film,and then an operation of wiping the particle mono-layer film is carriedout. The metal reaches the surface of the original substrate through agap in the particle mask during the vacuum deposition, but the metalimmediately below the particles is not deposited. Accordingly, when theparticles are wiped after the vacuum deposition, a mask, which isconstituted by a mesh-shaped metallic deposition layer in which anopening is formed at sites at which the particles are present, isformed.

When the mesh-shaped metallic layer is used as a mask of dry etching, aportion at which the metal is not present is etched, and thus amicrostructure surface, in which a number of convex holes are formed onthe surface, may be obtained.

The substrate 11 may be prepared in such a manner that the substratehaving a structure in which the plurality of convex portions areperiodically and two-dimensionally ordered on a surface is used as amold, and the structure in the mold surface is transferred onto theoriginal substrate in an even number of times.

The transfer of the structure of the mold surface may be carried out bymethods in the related art such as a nano imprint method, a thermalpressing method, an injection molding method, and an UV embossing methodthat are disclosed in Japanese Unexamined Patent Application, FirstPublication No. 2009-158478.

When the number of transfer times increases, a shape of the fineconcavity and convexity gets dull, and thus the practical number oftransfer times is preferably 2 or 4 times.

The organic light emitting diode 10 may be obtained by sequentiallylaminating the anodic conductive layer 12, the hole implantation layer13 a, the hole transport layer 13 b, the light emitting layer 13 c, theelectron transport layer 13 d, and the electron implantation layer 13 e,and the cathodic conductive layer 14 on the structure of the substrate11 prepared as described above.

A method of laminating these respective layers is not particularlylimited, and a method in the related art, which has been used in themanufacturing of a general organic light emitting diode, may be used.For example, the anodic conductive layer 12 and the cathodic conductivelayer 14 may be formed, respectively, by a sputtering method, a vacuumdeposition method, and the like. In addition, the hole implantationlayer 13 a, the hole transport layer 13 b, the light emitting layer 13c, the electron transport layer 13 d, and the electron implantationlayer 13 e are formed according to the vacuum deposition method.

Since the thickness of these respective layers is very small, when theselayers are sequentially laminated as described above, the structure onthe surface of the substrate 11 is reflected up to the cathodicconductive layer 14. Accordingly, the cathodic conductive layer 14,which has the two-dimensional periodic structure on a surface thereof onan organic EL layer 13 side, is formed.

Hereinbefore, the organic light emitting diode and the manufacturingmethod thereof of the first aspect of the invention has been describedwith reference to the embodiment shown in FIG. 1, but the invention isnot limited thereto.

For example, in the embodiment, the description has been made withrespect to an example in which the organic EL layer 13 is constituted byfive layers of the hole implantation layer 13 a, the hole transportlayer 13 b, the light emitting layer 13 c, the electron transport layer13 d, and the electron implantation layer 13 e, but the invention is notlimited thereto. For example, among the hole implantation layer 13 a,the hole transport layer 13 b, the light emitting layer 13 c, theelectron transport layer 13 d, and the electron implantation layer 13 e,one layer may have the functions of two more more layers. In addition,the light emitting layer 13 c is requisite, but the other layers, forexample, the hole implantation layer 13 a, the hole transport layer 13b, the electron transport layer 13 d, and the electron implantationlayer 13 e may be omitted. In the simplest system, the organic EL layer13 is constituted by only the light emitting layer 13 c.

In addition, the description has been made with respect to an example inwhich the electron implantation layer 13 e is provided. However, in acase where the cathodic conductive layer 14 also has a function of theelectron implantation layer, the electron implantation layer 13 e maynot be provided. For example, when the cathodic conductive layer 14 isconstituted by an magnesium alloy such as Mg/Ag=10/90, the electronimplantation effect is obtained as described above, and thus thecathodic conductive layer 14 also has the function of the electronimplantation layer.

<<Organic Light Emitting Diode of Second Aspect>>

In the organic light emitting diode of the second aspect of theinvention, at least a cathodic conductive layer formed from Ag or analloy containing 70% by mass or more of Ag, an organic EL layer thatincludes a light emitting layer containing an organic light emittingmaterial, and an anodic conductive layer are sequentially laminated on asubstrate. A two-dimensional lattice structure, in which a plurality ofconcave portions are periodically and two-dimensionally ordered, isprovided on a surface of the cathodic conductive layer on an organic ELlayer side.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the concave portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A, B,C, D, E, F, G, H, I, J, and A in a graph illustrating a relationshipbetween the light extraction wavelength and the distance, and the depthof the concave portions is 15 nm to 70 nm.

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called atop emission type. The organic light emitting diode is the same as theorganic light emitting diode of the first aspect except that thelamination sequence of the cathodic conductive layer, the organic ELlayer, and the anodic conductive layer on the substrate is reversed.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 5 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 20 of this embodiment, a cathodicconductive layer 14, an organic EL layer 13, and an anodic conductivelayer 12 are sequentially laminated on a substrate 21.

The organic EL layer 13 includes an electron implantation layer 13 e, anelectron transport layer 13 d, a light emitting layer 13 c, a holetransport layer 13 b, and a hole implantation layer 13 a that aresequentially laminated from the side of the cathodic conductive layer14.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 14.

In this aspect, a structure in which a plurality of concave portions 22are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 21 on a side at which the cathodic conductive layer 14is laminated. When the cathodic conductive layer 14 is laminated on thestructure, a structure that is the same as that of the surface of thesubstrate 21, that is, a structure (two-dimensional lattice structure)in which a plurality of concave portions 16 are periodically andtwo-dimensionally ordered is formed on the surface of the negativeconductive layer 14 on an organic EL layer 13 side.

As a material constituting the substrate 21, the same material as thesubstrate 11 may be exemplified. However, in this aspect, light isextracted from a side that is opposite to the substrate 21, and thus thesubstrate 21 may be not necessarily transparent.

The cathodic conductive layer 14, the organic EL layer 13, and theanodic conductive layer 12 are the same as the layers described above,respectively.

The organic light emitting diode 20 of this aspect may be manufacturedby the same manner as the organic light emitting diode 10 except thatthe cathodic conductive layer 14, the organic EL layer 13, and theanodic conductive layer 12 are sequentially laminated on the structureof the substrate 21 having a structure in which the plurality of concaveportions 22 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

Examples of a method for preparing the substrate 21 includephotolithography, electron beam photolithography, mechanical cutting,layer machining, two-beam interference exposure, reduction exposure, andthe like.

However, as described above, among the methods, methods other than thetwo-beam interference exposure is not suitable for manufacturing aperiodic lattice structure in a large area, and thus has restrictions onan area in an industrial use aspect. In addition, the two-beaminterference exposure may manufacture a substrate having a small area toa certain degree. However, in a case of an large area in which a side isseveral cm or more, the manufacturing is affected by various disturbancefactors such as vibration, wind, thermal expansion and shrinkage,fluctuation of air, and voltage variation with respect to the entiretyof optical setup, and thus it is very difficult to prepare a uniform,correct, and periodic lattice structure.

Therefore, in this aspect, in the manufacturing of the substrate 21, itis preferable to use the dry etching method in which the particlemono-layer film is used as an etching mask similar to the substrate 11.

The manufacturing of the substrate 21 by using the dry etching method inwhich the particle mono-layer film is used as the etching mask may becarried out, for example, by preparing a mold having a structure inwhich the plurality of convex portions corresponding to thetwo-dimensional lattice structure are periodically and two-dimensionallyordered on a surface according to the dry etching method in which theparticle mono-layer film is used as the etching mask, and by transferthe structure of the structure in the mold surface to the originalsubstrate in an odd number of times.

The preparation of the mold according to the dry etching method in whichthe particle mono-layer film is used as the etching mask may be carriedout in the same sequence as the manufacturing of the substrate in thefirst aspect.

The transfer of the structure of the mold surface may be carried out bymethods in the related art such as the nano imprint method, the thermalpressing method, the injection molding method, and the UV embossingmethod that are disclosed in Japanese Unexamined Patent Application,First Publication No. 2009-158478.

When the number of transfer times increases, a shape of the fineconcavity and convexity gets dull, and thus a practical number oftransfer times is preferably 1 or 3 times.

In addition, as another method, a method in which a metallic mesh maskprepared using the particle mono-layer film is used may be exemplified.That is, the particle mono-layer film is prepared on a surface of theoriginal substrate, a metal such as Cr, Ni, Fe, and Co isvacuum-deposited from an upper side of the particle mono-layer film, andthen an operation of wiping the particle mono-layer film is carried out.The metal reaches the surface of the original substrate through a gap inthe particle mask during the vacuum deposition, but the metalimmediately below the particles is not deposited. Accordingly, when theparticles are wiped after the vacuum deposition, a mask, which isconstituted by a mesh-shaped metallic deposition layer in which anopening is formed at sites at which the particles are present, isformed.

When the mesh-shaped metallic layer is used as a mask of dry etching, aportion at which the metal is not present is etched, and thus amicrostructure surface, in which a number of concave holes are formed onthe surface, may be obtained.

<<Organic Light Emitting Diode of Third Aspect>>

In the organic light emitting diode of the third aspect of theinvention, at least an anodic conductive layer, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and a cathodic conductivelayer formed from Ag or an alloy containing 70% by mass or more of Agare sequentially laminated on a substrate. A two-dimensional latticestructure, in which a plurality of convex portions are periodically andtwo-dimensionally ordered, is provided on a surface of the cathodicconductive layer on an organic electroluminescence layer side.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the convex portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A, B,C, D, E, F, G, H, I, J, and A in a graph illustrating a relationshipbetween the light extraction wavelength and the distance, and the heightof the convex portions is 12 nm to 180 nm.

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called abottom emission type. The organic light emitting diode is the same asthe organic light emitting diode of the first aspect except that theconvex portions of the substrate of the organic light emitting diode ofthe first aspect are changed to concave portions, and the concaveportions on the surface of the cathodic conductive layer on the organicEL layer side are changed to convex portions.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 8 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 110 of this embodiment, an anodicconductive layer 12, an organic EL layer 13, and a cathodic conductivelayer 14 are sequentially laminated on a substrate 111.

The organic EL layer 13 includes a hole implantation layer 13 a, a holetransport layer 13 b, a light emitting layer 13 c, an electron transportlayer 13 d, and an electron implantation layer 13 e that aresequentially laminated from the side of the anodic conductive layer 12.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 14.

In this aspect, a structure in which a plurality of concave portions 22are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 111 on a side at which the anodic conductive layer 12is laminated. When the anodic conductive layer 12, the organic EL layer13 (the hole implantation layer 13 a, the hole transport layer 13 b, thelight emitting layer 13 c, the electron transport layer 13 d, and theelectron implantation layer 13 e) are sequentially laminated on thestructure, the same structure as the surface of the substrate 111 isformed on surfaces of the respective layers on a cathodic conductivelayer 14 side. Accordingly, when the cathodic conductive layer 14 isfinally laminated on the organic EL layer 13, a structure inverted fromthe structure of the surface of the substrate 111, that is, atwo-dimensional lattice structure, in which a plurality of convexportions 116 are periodically and two-dimensionally ordered, is formedon a surface of the cathodic conductive layer 14 on an organic EL layer13 side.

As a material constituting the substrate 111, the same material as thesubstrate 11 may be exemplified.

The cathodic conductive layer 14, the organic EL layer 13, and theanodic conductive layer 12 are the same as the layers described above,respectively.

The organic light emitting diode 110 of this aspect may be manufacturedby the same manner as the organic light emitting diode 10 except thatthe anodic conductive layer 12 is laminated on the structure of thesubstrate 111 having a structure in which the plurality of concaveportions 22 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

The substrate 111 may be manufactured in the same manner as thesubstrate 21 of the second aspect, and a preferred manufacturing methodis the same as the preferred manufacturing method of the substrate 21.

<<Organic Light Emitting Diode of Fourth Aspect>>

In the organic light emitting diode of the fourth aspect of theinvention, at least a cathodic conductive layer formed from Ag or analloy containing 70% by mass or more of Ag, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and an anodic conductivelayer are sequentially laminated on a substrate. A two-dimensionallattice structure, in which a plurality of convex portions areperiodically and two-dimensionally ordered, is provided on a surface ofthe cathodic conductive layer on an organic electroluminescence layerside.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the convex portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A, B,C, D, E, F, G, H, I, J, and A in a graph illustrating a relationshipbetween the light extraction wavelength and the distance, and the heightof the convex portions is 12 nm to 180 nm.

A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C (λ=600, p=406+W(½)), D(λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F (λ=800, p=493−W(½)), G(λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I (λ=500, p=262−W(½)), and J(λ=450, p=110−W(½)), in which W(½) represents a half width at halfmaximum of a light emitting peak in a spectrum of the light emittingmaterial that constitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called atop emission type. The organic light emitting diode is the same as theorganic light emitting diode of the second aspect except that theconcave portions of the substrate of the organic light emitting diode ofthe second aspect are changed to convex portions, and the convexportions on the surface of the cathodic conductive layer on the organicEL layer side are changed to concave portions.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 9 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 120 of this embodiment, a cathodicconductive layer 14, an organic EL layer 13, and an anodic conductivelayer 12 are sequentially laminated on a substrate 121.

The organic EL layer 13 includes an electron implantation layer 13 e, anelectron transport layer 13 d, a light emitting layer 13 c, a holetransport layer 13 b, and a hole implantation layer 13 a that aresequentially laminated from the side of the cathodic conductive layer14.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 14.

In this aspect, a structure in which a plurality of convex portions 15are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 121 on a side at which the cathodic conductive layer 14is laminated. When the cathodic conductive layer 14 is laminated on thestructure, a structure that is the same as the surface of the substrate121, that is, a structure (two-dimensional lattice structure) in which aplurality of convex portions 116 are periodically and two-dimensionallyordered is formed on a surface of the cathodic conductive layer 14 on anorganic EL layer 13 side.

As a material constituting the substrate 121, the same materials as thesubstrate 21 are exemplary examples.

The cathodic conductive layer 14, the organic EL layer 13, and theanodic conductive layer 12 are the same as the layers described above,respectively.

The organic light emitting diode 120 of this aspect may be manufacturedby the same manner as the organic light emitting diode 20 except thatthe cathodic conductive layer 14 is laminated on the structure of thesubstrate 121 having a structure in which the plurality of convexportions 15 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

The substrate 121 may be manufactured in the same manner as thesubstrate 11 of the first aspect, and a preferred manufacturing methodis the same as the preferred manufacturing method of the substrate 11.

<<Organic Light Emitting Diode of Fifth Aspect>>

In the organic light emitting diode of the fifth aspect of theinvention, at least an anodic conductive layer, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and a cathodic conductivelayer formed from Al or an alloy containing 70% by mass or more of Alare sequentially laminated on a substrate, and a two-dimensional latticestructure, in which a plurality of concave portions are periodically andtwo-dimensionally ordered, is provided on a surface of the cathodicconductive layer on an organic electroluminescence layer side.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the concave portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A′, B′,C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in a graph illustrating arelationship between the light extraction wavelength and the distance,and the depth of the concave portions is 12 nm to 180 nm.

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called abottom emission type. The organic light emitting diode is the same asthe organic light emitting diode of the first aspect except that thematerial of the cathodic conductive layer of the organic light emittingdiode of the first aspect is changed from Ag or an alloy containing 70%by mass or more of Ag to Al or an alloy containing 70% by mass or moreof Al, and the distance p between the centers of the plurality ofconcave portions of the cathodic conductive layer is changed to theabove-described range.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 1 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 210 of this embodiment, an anodicconductive layer 12, an organic EL layer 13, and a cathodic conductivelayer 214 formed from Al or an alloy containing 70% by mass or more ofAl are sequentially laminated on a substrate 11.

The organic EL layer 13 includes a hole implantation layer 13 a, a holetransport layer 13 b, a light emitting layer 13 c, an electron transportlayer 13 d, and an electron implantation layer 13 e that aresequentially laminated from the side of the anodic conductive layer 12.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 214.

In this aspect, a structure, in which a plurality of convex portions 15are periodically and two-dimensionally ordered, is provided on a surfacethe substrate 11 on a side at which the anodic conductive layer 12 islaminated. When the anodic conductive layer 12, the organic EL layer 13(the hole implantation layer 13 a, the hole transport layer 13 b, thelight emitting layer 13 c, the electron transport layer 13 d, and theelectron implantation layer 13 e) are sequentially laminated on thestructure, the same structure as the surface of the substrate 11 isformed on surfaces of the respective layers on a cathodic conductivelayer 214 side. Accordingly, when the cathodic conductive layer 214 isfinally laminated on the organic EL layer 13, a structure inverted fromthe structure of the surface of the substrate 11, that is, atwo-dimensional lattice structure, in which a plurality of concaveportions 16 are periodically and two-dimensionally ordered, is formed ona surface of the cathodic conductive layer 214 on an organic EL layer 13side.

[Cathodic Conductive Layer 214]

The cathodic conductive layer 214 is formed from Al or an alloycontaining 70% by mass or more of Al.

The thickness of the cathodic conductive layer 214 is commonly 50 to3,000 nm.

The substrate 11, the anodic conductive layer 12, and the organic ELlayer 13 are the same as the layers described above.

The shorter the distance from the surface of the cathodic metallic layeron a light emitting layer side to the light emitting layer is, thelarger a percentage of conversion from energy of the surface plasmoninto light by light emitting energy is.

The invention is particularly effective with respect to an organic lightemitting diode in which a percentage of energy converted into thesurface plasmon is large. The invention is effective for an organiclight emitting diode in which a distance from the surface of thecathodic metallic layer on a light emitting layer side to the lightemitting layer is, for example, 100 nm or less, and as a relativelyshort distance, for example, 50 nm or less.

In the fifth aspect of the invention, the extraction wavelength λ (nm)of light from the organic light emitting diode 210 and the distance p(nm) between the centers of the concave portions 16 in thetwo-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A′, B′,C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in a graph illustrating arelationship between the light extraction wavelength and the distance.In addition, the depth of the concave portions 16 is 12 nm to 180 nm,and more preferably 15 nm to 70 nm. Accordingly, the light extractionefficiency is significantly improved.

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½))

W(½) has the same meaning as W(½) in the first aspect.

The distance p (nm) between the centers of the concave portions 16 isdetermined by the extraction wavelength λ (nm).

The extraction wavelength λ (nm) is a wavelength when energy isextracted from the surface plasmon as radiant light, and most commonly,the λ (nm) is an emission peak wavelength of the light emittingmaterial.

When a specific extraction wavelength is λ₁ [λ₁ is a specific valuewithin a range of 300 nm to 800 nm], the distance p between the centersof the concave portions 16 may take an arbitrary value corresponding toa coordinate of λ=λ₁ within the above-described region. For example, ina case where λ₁ is 600 nm, the distance p may take an arbitrary valuefrom [368−W(½)] nm to [438+W(½)] nm.

The relationship between the extraction wavelength λ (nm) and thedistance p (nm) between the centers of the concave portions 16 will bedescribed in more detail with reference to FIG. 10.

FIG. 10 shows a graph in which the extraction wavelength λ (nm) is shownin the horizontal axis, and the distance p (nm) between the centers ofthe concave portions is shown in the vertical axis.

As shown in FIG. 10, the coordinates A′, B′, C′, D′, E′, and F′ arecoordinates that are obtained by shifting p of coordinates (λ, p) of(300, 220), (400, 295), (500, 368), (600, 438), (700, 508), and (800,575) in a positive direction by W(½), respectively. The coordinates G′,H′, I′, J′, K′, and L′ are coordinates that are obtained by shifting thedistance p of coordinates (λ, p) of (800, 505), (700, 438), (600, 368),(500, 298), (400, 225), and (300, 150) in a negative direction by W(½),respectively. When the shift width exceeds W(½), the light extractionefficiency is improved, but the effect is greatly inferior to a casewhere the shift width is within W(½).

The smaller the shift width is, the more preferable. It is preferablethat the shift width be ⅕ W, more preferably 1/10 W, and still morepreferably 0. That is, it is particularly preferable that the extractionwavelength λ (nm) and the distance p (nm) between the centers of theconcave portions 16 be within a region surrounded by straight linessequentially connecting coordinates (λ, p) of (300, 220), (400, 295),(500, 368), (600, 438), (700, 508), (800, 575), (800, 505), (700, 438),(600, 368), (500, 298), (400, 225), and (300, 150) in a graphillustrating the relationship between the extraction wavelength and thedistance.

The coordinates of 12 points of A′ to L′ are obtained by calculatingconversion efficiency from the surface plasmon to light. In addition,practically, a significant improvement in the light extractionefficiency when the extraction wavelength and the distance are withinthe region surrounded by straight lines sequentially connecting thecoordinates of the 12 points was confirmed with regard to a case wherethe extraction wavelength λ is 470 nm in [Examples] to be describedlater.

In the following description, the calculation method described in thefirst aspect is applicable to a calculation method of conversionefficiency from the surface plasmon to light for specifying theabove-described coordinates. With regard to the cathodic conductivelayer 14 in the model shown in FIG. 3, the calculation may be carriedout by changing silver to aluminum.

Here, the reflectance is calculated by assuming the refractive index nof the organic EL layer as 1.6, 1.7, or 1.8 and by systematicallychanging the distance p between the centers of the holes and depth d ofthe holes with respect to cases where the wavelength (corresponding tothe extraction wavelength λ) of the monochromatic plane wave is 300 nm,400 nm, 500 nm, 600 nm, 700 nm, and 800 nm.

In addition, among the above-described coordinates, coordinates at whichthe reflectance becomes the minimum value when the refractive index n is1.6 include coordinates (λ, p) of (300, 220), (400, 295), (500, 368),(600, 438), (700, 508), and (800, 575), and coordinates at which thereflectance becomes the minimum value when the refractive index n is 1.8include coordinates (λ, P) of (300, 150), (400, 225), (500, 298), (600,368), (700, 438), and (800, 505). Coordinates at which the reflectancebecomes the minimum value when the refractive index n is 1.7 areapproximately intermediate values between the case where the refractiveindex n is 1.6 and the case where the refractive index n is 1.8.

In addition, in the case of the organic light emitting diode 210, theconversion efficiency from the surface plasmon to light, and therefractive index may be obtained in the same manner as the case whereFIGS. 3A, 3B, and 4A to 4C are used in the organic light emitting diode10.

The organic light emitting diode 210 of this aspect may be manufacturedin the same manner as the organic light emitting diode 10 except thatthe cathodic conductive layer 214 is laminated on the organic EL layer13.

The substrate 11 of this aspect may be manufactured in the same manneras the substrate 11 of the first aspect, and a preferred manufacturingmethod is the same as the preferred manufacturing method of thesubstrate 11 of the first aspect.

<<Organic Light Emitting Diode of Sixth Aspect>>

In the organic light emitting diode of the second aspect of theinvention, at least a cathodic conductive layer formed from Al or analloy containing 70% by mass or more of Al, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and an anodic conductivelayer are sequentially laminated on a substrate. A two-dimensionallattice structure, in which a plurality of concave portions areperiodically and two-dimensionally ordered, is provided on a surface ofthe cathodic conductive layer on an organic electroluminescence layerside. An extraction wavelength λ (nm) of light from the organic lightemitting diode and a distance p (nm) between centers of the concaveportions in the two-dimensional lattice structure are within a regionsurrounded by straight lines sequentially connecting the followingcoordinates A′, B′, C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in agraph illustrating a relationship between the light extractionwavelength and the distance, and the depth of the concave portions is 12nm to 180 nm.

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called atop emission type. The organic light emitting diode is the same as theorganic light emitting diode of the fifth aspect except that thelamination sequence of the cathodic conductive layer, the organic ELlayer, and the anodic conductive layer on the substrate is reversed.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 5 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 220 of this embodiment, a cathodicconductive layer 214, an organic EL layer 13, and an anodic conductivelayer 12 are sequentially laminated on a substrate 21.

The organic EL layer 13 includes an electron implantation layer 13 e, anelectron transport layer 13 d, a light emitting layer 13 c, a holetransport layer 13 b, and a hole implantation layer 13 a that aresequentially laminated from the side of the cathodic conductive layer214.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 214.

In this aspect, a structure in which a plurality of concave portions 22are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 21 on a side at which the cathodic conductive layer 214is laminated. When the cathodic conductive layer 214 is laminated on thestructure, a structure that is the same as the surface of the substrate21, that is, a structure (two-dimensional lattice structure) in which aplurality of concave portions 16 are periodically and two-dimensionallyordered is formed on a surface of the cathodic conductive layer 214 onan organic EL layer 13 side.

The substrate 21, the cathodic conductive layer 214, and the organic ELlayer 13, and the anodic conductive layer 12 are the same as the layersdescribed above, respectively.

The organic light emitting diode 220 of this aspect may be manufacturedby the same manner as the organic light emitting diode 20 except thatthe cathodic conductive layer 214, the organic EL layer 13, and theanodic conductive layer 12 are sequentially laminated on the structureof the substrate 21 having a structure in which the plurality of concaveportions 22 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

<<Organic Light Emitting Diode of Seventh Aspect>>

In the organic light emitting diode of the seventh aspect of theinvention, at least an anodic conductive layer, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and a cathodic conductivelayer formed from Al or an alloy containing 70% by mass or more of Alare sequentially laminated on a substrate, and a two-dimensional latticestructure, in which a plurality of convex portions are periodically andtwo-dimensionally ordered, is provided on a surface of the cathodicconductive layer on an organic electroluminescence layer side.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the convex portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A′, B′,C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in a graph illustrating arelationship between the light extraction wavelength and the distance,and the height of the convex portions is 12 nm to 180 nm.

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called abottom emission type. The organic light emitting diode is the same asthe organic light emitting diode of the fifth aspect except that theconvex portions of the substrate of the organic light emitting diode ofthe fifth aspect are changed to concave portions, and the concaveportions on the surface of the cathodic conductive layer on the organicEL layer side are changed to convex portions.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.

FIG. 8 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 310 of this embodiment, an anodicconductive layer 12, an organic EL layer 13, and a cathodic conductivelayer 214 are sequentially laminated on a substrate 111.

The organic EL layer 13 includes a hole implantation layer 13 a, a holetransport layer 13 b, a light emitting layer 13 c, an electron transportlayer 13 d, and an electron implantation layer 13 e that aresequentially laminated from the side of the anodic conductive layer 12.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 214.

In this aspect, a structure in which a plurality of concave portions 22are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 111 on a side at which the anodic conductive layer 12is laminated. When the anodic conductive layer 12, the organic EL layer13 (the hole implantation layer 13 a, the hole transport layer 13 b, thelight emitting layer 13 c, the electron transport layer 13 d, and theelectron implantation layer 13 e) are sequentially laminated on thestructure, the same structure as the surface of the substrate 111 isformed on surfaces of the respective layers on a cathodic conductivelayer 214 side. Accordingly, when the cathodic conductive layer 214 isfinally laminated on the organic EL layer 13, a structure inverted fromthe structure of the surface of the substrate 111, that is, atwo-dimensional lattice structure, in which a plurality of convexportions 116 are periodically and two-dimensionally ordered, is formedon a surface of the cathodic conductive layer 214 on an organic EL layer13 side.

The substrate 111, the cathodic conductive layer 214, the organic ELlayer 13, and the anodic conductive layer 12 are the same as the layersdescribed above, respectively.

The organic light emitting diode 310 of this aspect may be manufacturedby the same manner as the organic light emitting diode 210 except thatthe anodic conductive layer 12 is laminated on the structure of thesubstrate 111 having a structure in which the plurality of concaveportions 22 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

The substrate 111 may be manufactured in the same manner as thesubstrate 21 of the second aspect, and a preferred manufacturing methodis the same as the preferred manufacturing method of the substrate 21.

<<Organic Light Emitting Diode of Eighth Aspect>>

In the organic light emitting diode of the eighth aspect of theinvention, at least a cathodic conductive layer formed from Al or analloy containing 70% by mass or more of Al, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and an anodic conductivelayer are sequentially laminated on a substrate, and a two-dimensionallattice structure, in which a plurality of convex portions areperiodically and two-dimensionally ordered, is provided on a surface ofthe cathodic conductive layer on an organic electroluminescence layerside.

An extraction wavelength λ (nm) of light from the organic light emittingdiode and a distance p (nm) between centers of the convex portions inthe two-dimensional lattice structure are within a region surrounded bystraight lines sequentially connecting the following coordinates A′, B′,C′, D′, E′, F′, G′, H′, I′, J′, K′, L′, and A′ in a graph illustrating arelationship between the light extraction wavelength and the distance,and the height of the convex portions is 12 nm to 180 nm.

A′ (λ=300, p=220+W(½)), B′ (λ=400, p=295+W(½)), C′ (λ=500, p=368+W(½)),D′ (λ=600, p=438+W(½)), E′ (λ=700, p=508+W(½)), F′ (λ=800, p=575+W(½)),G′ (λ=800, p=505−W(½)), H′ (λ=700, p=438−W(½)), I′ (λ=600, p=368−W(½)),J′ (λ=500, p=298−W(½)), K′ (λ=400, p=225−W(½)), and L′ (λ=300,p=150−W(½)), in which W(½) represents a half width at half maximum of alight emitting peak in a spectrum of the light emitting material thatconstitutes the light emitting layer.

The organic light emitting diode of this aspect is an organic lightemitting diode having a layer configuration of a type generally called atop emission type. The organic light emitting diode is the same as theorganic light emitting diode of the sixth aspect except that the concaveportions of the substrate of the organic light emitting diode of thesixth aspect are changed to convex portions, and the convex portions onthe surface of the cathodic conductive layer on the organic EL layerside are changed to concave portions.

Hereinafter, the organic light emitting diode of this aspect will bedescribed with reference to the attached drawings. In addition, in thefollowing embodiment, the same reference numerals are given to the sameparts corresponding to the configuration shown in the drawings shownpreviously, and a detailed description thereof will be omitted here.FIG. 9 shows a partial schematic cross-sectional diagram illustrating aconfiguration of an embodiment of the organic light emitting diode ofthis aspect.

In the organic light emitting diode 320 of this embodiment, a cathodicconductive layer 214, an organic EL layer 13, and an anodic conductivelayer 12 are sequentially laminated on a substrate 121.

The organic EL layer 13 includes an electron implantation layer 13 e, anelectron transport layer 13 d, a light emitting layer 13 c, a holetransport layer 13 b, and a hole implantation layer 13 a that aresequentially laminated from the side of the cathodic conductive layer214.

A voltage may be applied to the anodic conductive layer 12 and thecathodic conductive layer 214.

In this aspect, a structure in which a plurality of convex portions 15are periodically and two-dimensionally ordered is provided on a surfaceof the substrate 121 on a side at which the cathodic conductive layer214 is laminated. When the cathodic conductive layer 214 is laminated onthe structure, a structure that is the same as the surface of thesubstrate 121, that is, a structure (two-dimensional lattice structure)in which a plurality of convex portions 116 are periodically andtwo-dimensionally ordered is formed on a surface of the cathodicconductive layer 214 on an organic EL layer 13 side.

The substrate 121, the cathodic conductive layer 214, the organic ELlayer 13, and the anodic conductive layer 12 are the same as the layersdescribed above, respectively.

The organic light emitting diode 320 of this aspect may be manufacturedby the same manner as the organic light emitting diode 220 except thatthe cathodic conductive layer 214 is laminated on the structure of thesubstrate 121 having a structure in which the plurality of convexportions 15 corresponding to the two-dimensional lattice structure areperiodically and two-dimensionally ordered on a surface.

The substrate 121 may be manufactured in the same manner as thesubstrate 11 of the first aspect, and a preferred manufacturing methodis the same as the preferred manufacturing method of the substrate 11.

As described above, in the organic light emitting diodes of the first toeighth aspects of the invention, the light extraction efficiency issignificantly improved, and thus high-intensity light emission may beobtained.

In addition, in a case where the two-dimensional lattice structure is asquare lattice, it is preferable to make a correction by multiplyingcoordinate values of the distance p (nm) between the centers of theconcave portions or the distance p (nm) between the centers of theconvex portions by (√3/2). In addition, in an organic light emittingdiode of this aspect, the light extraction efficiency is alsosignificantly improved, and high-intensity light emission may beobtained.

Accordingly, the organic light emitting diodes of the invention areuseful in an image display device, an illuminating device, and the like.A low-voltage operation is possible, and thus lifetime of the organic ELelement may be significantly increased, and thus saving of energy isrealized. Furthermore, the light extraction efficiency is high, and thusa bright image display device or illuminating device may be obtained.

EXAMPLES

Hereinafter, an example of the embodiments of the invention will bedescribed. The structure, configuration, and type of the organic lightemitting diode that is an object is not necessarily limited as long asthe concept of the invention is used.

Example 1

An aqueous dispersion (dispersed solution) of spherical colloidal silicaof 5.0% by mass in which an average particle size is 395.0 nm, and avariation coefficient of a particle size is 4.0% was prepared. Inaddition, the average particle size and the variation coefficient of theparticle size were obtained from a peak obtained by fitting a particlesize distribution, which was obtained by a particle dynamic scatteringmethod using Zetasizer Nano-ZS manufactured by Malvern Instruments Ltd.,to a Gauss curve.

Next, the dispersed solution was filtered by a membrane filter having ahole diameter of 1.2 μmφ, an aqueous hydrolysis solution ofphenyltriethoxysilane having a concentration of 1.0% by mass was addedto the dispersed solution passed through the membrane filter, andreaction was carried out at approximately 40° C. for 3 hours. At thistime, the dispersion solution and the aqueous hydrolysis solution weremixed in such a manner that the mass of the phenyltriethoxysilane was0.015 times the mass of the colloidal silica particles.

Next, methyl isobutyl ketone having a volume 5 times a volume of thedispersed solution was added to the dispersed solution obtained aftercompletion of the reaction, the resultant mixture was sufficientlystirred, and oil-phase extraction of the colloidal silica that washydrophobized was carried out.

The hydrophobized colloidal silica dispersed solution having aconcentration of 1.05% by mass, which was obtained in this manner, wasadded dropwise at a dropwise addition rate of 0.01 mL/second to a liquidsurface (water was used as the lower-layer water, and the watertemperature was 26.5° C.) in a water tank (LB trough apparatus) providedwith a surface-pressure sensor that measures a surface pressure of theparticle mono-layer film, and a movable barrier that compresses theparticle mono-layer film in a direction along the liquid surface. Inaddition, a quartz substrate (30 mm×30 mm×1.0 mm, both surfaces weremirror-polished) to be used as a transparent substrate of the organiclight emitting diode was immersed in advance in the lower-layer water ofthe water tank in an approximately vertical direction.

Then, in the lower-layer water, ultrasonic waves (an output of 100 W, afrequency of 1,500 kHz) were emitted toward the water surface for 10minutes to vaporize the methyl isobutyl ketone that is a solvent of thedispersed solution while promoting two-dimensional close packing of theparticles, whereby a particle mono-layer film was formed.

Next, the particle mono-layer film was compressed by the movable barrieruntil a diffusion pressure became 22 to 30 mNm⁻¹, and the quartzsubstrate was pulled at a velocity of 3 mm/minute to move the particlemono-layer film on the water surface onto a surface of the substrate.

Next, a hydrolysis solution of monomethyltrimethoxysilane of 0.15% bymass as a binder was allowed to infiltrate into the quartz substrate onwhich the particle mono-layer film was formed, and then the surplus ofthe hydrolysis solution was removed by treatment of a spin coater (3,000rpm) for 1 minute. Then, the substrate was heated at 100° C. for 10minutes to carry out the reaction of the binder, whereby a quartsubstrate to which the particle mono-layer film formed from thecolloidal silica was attached was obtained.

Next, the obtained quartz substrate to which the particle mono-layerfilm was attached was subjected to dry etching by a CHF₃ gas. Withregard to conditions of the dry etching, the antenna power was set to1,500 W, the bias power was set to 50 to 300 W (13.56 MHz), and the gasflow rate was set to 50 to 200 sccm.

After the dry etching, a surface of the substrate that was obtained wasobserved by an atomic force microscope (AFM), and it could be seen thata microstructure, in which convex portions having a truncated conicalcross-sectional shape as shown in FIG. 6 were disposed in a triangularlattice shape, was formed.

The distance p′ (lattice constant) between the centers of the convexportions in the microstructure formed in the substrate surface asdescribed above was measured by a laser diffraction method, and afterperforming a test three times, an average value was 395.0 nm. Inaddition, with regard to an average height h of the convex portions inthe microstructure, an average value was obtained in each of total 25sites of regions of 5 μm×5 μm randomly selected from an AFM image, andthe respective average values of the 25 sites were further averaged.Form the calculation, the average height h was 30.9 nm. In addition, adeviation D′ in arrangement was 4.9%. In addition, the ratio between theaverage height h and the average value of the distance P′ between thecenters (the distance p′ between the centers/the average height h) thatwas calculated from the obtained values was 0.078.

IZO as an anodic conductive layer was formed on the quartz substrate ona microstructure surface side in a thickness of 50 nm by a sputteringmethod. Next, as a hole implantation material,4,4′,4″-tris(N,N-2-naphthylphenylamino)triphenylamine (2-TNATA) wasformed in a thickness of 30 nm according to a deposition method. Next,as a hole transport material,4,4′-bis[N-1-napthyl]-N-phenyl-amino]-biphenyl(α-NPD) was formed in athickness of 70 nm according to a deposition method. Next, as anelectron transport and light emitting layer, a material obtained bydoping a host material (PH1) with Tris[1-phenylisoquinoline-C2,N]iridium (III) (Ir(piq)₃) in a concentration of 5% was formed in athickness of 30 nm according to a deposition method. Next, as anelectron transport layer, Tris(8-quinolinolato)aluminum (Alq) was formedin a thickness of 30 nm according to a deposition method. Finally, as acathodic conductive layer, a magnesium/silver alloy of Mg/Ag=10/90 (massratio) was formed at a thickness of 150 nm according to a depositionmethod, whereby a bottom emission type organic light emitting diode wascompleted. A light emitting area of 2×2 mm was prepared using a shadowmask in the deposition.

Example 2

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 1 except that dry etching conditionswere changed, was obtained.

At this time, the distance between the centers of convex portions of themicrostructure formed on the surface of the quartz substrate was 395.0nm, and the average height of the convex portions was 100 nm.

Comparative Example 1

A bottom emission type organic light emitting diode was obtained by thesame operation as Example 1 except that the microstructure was notformed on the surface of the quartz substrate. Accordingly, thesubstrate surface of this element was flat.

Comparative Example 2

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 1 except that the average particle sizeof the spherical colloidal silica was changed, was obtained.

At this time, the distance between the centers of convex portions of themicrostructure formed on the surface of the quartz substrate was 306.9nm, and the average height of the convex portions was 30.9 nm. Inaddition, the deviation D′ was 11.01%.

Comparative Example 3

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 1 except that the dry etchingconditions were changed, was obtained.

At this time, the distance between the centers of convex portions of themicrostructure formed on the surface of the quartz substrate was 395.0nm, and the average height of the convex portions was 10.2 nm. Inaddition, the deviation D′ in arrangement was 4.9%.

Comparative Example 4

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 1 except that the dry etchingconditions were changed, was obtained.

At this time, the distance between the centers of convex portions of themicrostructure formed on the surface of the quartz substrate was 395.0nm, and the average height of the convex portions was 192.0 nm.

Test Example 1 1. Preparation of Graph Illustrating Relationship betweenExtraction Wavelength λ (nm) and Distance p (nm) between Centers ofConcave Portions in Two-Dimensional Lattice Structure in Surface ofCathodic Conductive Layer

With respect to the bottom emission type organic light emitting diodesobtained in Examples 1 and 2, and Comparative Examples 1 to 4, a halfwidth at half maximum W(½) of a peak in an emission spectrum of a lightemitting material (material obtained by doping PH1 with Ir(piq)₃ in aconcentration of 5%) constituting the light emitting layer was obtainedby drawing on peaks, and W(½) was 40 nm. Coordinates A to J in a casewhere W(½) was 40 nm are shown in FIG. 7.

In addition, the extraction wavelength in the configurations of thebottom emission type organic light emitting diodes obtained in Examples1 and 2, and Comparative Examples 1 to 4 was obtained by waveformseparation of the emission spectrum, and the extraction wavelength was625 nm.

Accordingly, a range of the distance p between the centers of theconcave portions within a region surrounded by the coordinates A to Jcorresponding to the extraction wavelength of 625 nm was 335 nm to 467nm.

In the bottom emission type organic light emitting diodes obtained inExamples 1 and 2, and Comparative Examples 1 to 4, the distance betweenthe centers of the convex portions and the average height in themicrostructure formed on the surface of the quartz substrate are equalto the distance between the centers of the concave portions and theaverage depth in the two-dimensional periodic structure formed on asurface of the cathodic conductive layer, which is laminated on themicrostructure, on an electron transport layer side.

Accordingly, the bottom emission type organic light emitting diode ofExample 1, in which the distance between the centers of the concaveportions is 395.0 nm that is within a range of 335 nm to 467 nm, and thedepth of the concave portions is 30.9 nm, is within a range of theinvention. In addition, the bottom emission type organic light emittingdiode of Example 2, in which the distance between the centers of theconcave portions is 395.0 nm similar to Example 1, and the depth of theconcave portions is 100 nm, is within the range of the invention. On theother hand, since the distance between the centers of the concaveportions is 306.9 nm, the bottom emission type organic light emittingdiode of Comparative Example 2 is out of the range of the invention.Since the depth of the concave portions is 10.2 nm, the bottom emissiontype organic light emitting diode of Comparative Example 3 is out of therange of the invention. Since the depth of the concave portions is 192.0nm, the bottom emission type organic light emitting diode of ComparativeExample 4 is out of the range of the invention.

2. Evaluation of Luminous Efficiency Characteristics and LuminanceCharacteristics

With respect to each of the bottom emission type organic light emittingdiodes obtained in Examples 1 and 2, and Comparative Examples 1 to 4,the luminous efficiency characteristics and luminance characteristicswere evaluated in the following order.

When the bottom emission type organic light emitting diodes were causedto emit light with a current density of 30 mA/cm², the luminance (cd/m²)in a vertical direction was measured by a luminance meter, and theluminance characteristics per current density (current density(mA/cm²)−luminance (cd/m²)) were obtained. In addition, the voltage wasmeasured during the measurement of the luminance. The luminance wasconverted into a luminous flux (lm), and the luminous efficiency percurrent density (current density (mA/cm²)−luminous efficiency (lm/W))was obtained.

With respect to each of the luminous efficiency per current density andthe luminance, from the measurement results, a progress rate ofmeasurement values of Example 1 against measurement values ofComparative Example 1 was calculated by the following expression. Withrespect to Example 2, and Comparative Examples 2 to 4, a progress rateof measurement values thereof against the measurement values ofComparative Example 1 was also calculated. The results are shown inTable 1.

Progress Rate=(measurement values of Example 1−measurement values ofComparative Example 1)/measurement values of Comparative Example 1×100

TABLE 1 Microstructure of Evaluation of characteristics substratesurface Luminous efficiency Luminance Distance Height Against Againstbetween (or Measurement comparative Measurement comparative centersdepth) value example value example [nm] [nm] [lm/W] [%] [cd/cm²] [%]Example 1 395.0 30.9 2.88 +113.3 3991 +103.2 Example 2 395.0 100 3.08+128.1 3339 +70.0 Comparative — — 1.35 — 1964 — Example 1 Comparative306.9 30.9 1.42 +5.2 1995 +1.6 Example 2 Comparative 395.0 10.2 1.47+8.9 2244 +14.3 Example 3 Comparative 395.0 192.0 1.6 +18.5 1984 +1.0Example 4 * Current density: 30.0 mA/cm²

As shown in the results, in the bottom emission type organic lightemitting diodes of Examples 1 and 2, emission intensity greatlyincreased compared to Comparative Examples 1 to 4. Furthermore, currentdensity−luminous efficiency characteristics, and currentdensity−luminance characteristics were greatly improved.

Example 3

A bottom emission type organic light emitting diode was obtained by thesame operation as Example 1 except that the substrate was prepared bychanging the average particle size of the spherical colloidal silica andthe dry etching conditions, and as a light emitting material, a materialobtained by doping the host material (Alq₃) with Rubrene in aconcentration of 1% was used.

At this time, the distance between the centers of the convex portions ofthe microstructure formed on the surface of the quartz substrate was350.0 nm, and the average height of the convex portions was 70 nm.

Comparative Example 5

A bottom emission type organic light emitting diode was obtained by thesame operation as Example 3 except that the microstructure was notformed on the surface of the quartz substrate. Accordingly, thesubstrate surface of this element was flat.

Comparative Example 6

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 3 except that the average particle sizeof the spherical colloidal silica was changed, was obtained.

At this time, the distance between the centers of the convex portions ofthe microstructure formed on the surface of the quartz substrate was500.0 nm, and the average height of the convex portions was 70 nm.

Test Example 2 1. Preparation of Graph Illustrating Relationship betweenExtraction Wavelength λ (nm) and Distance p (nm) between Centers ofConcave Portions in Two-Dimensional Lattice Structure in Surface ofCathodic Conductive Layer

With respect to the bottom emission type organic light emitting diodesobtained in Example 3, and Comparative Examples 5 and 6, a half width athalf maximum W(½) of a peak in an emission spectrum of a light emittingmaterial (material obtained by doping the host material (Alq₃) withRubrene in a concentration of 1%) constituting the light emitting layerwas obtained by drawing on peaks, and W(½) was 40 nm. Coordinates A to Jin a case where W(½) was 40 nm are shown in FIG. 7.

In addition, the extraction wavelength in the configurations of thebottom emission type organic light emitting diodes obtained in Example3, and Comparative Examples 5 and 6 was obtained by waveform separationof the emission spectrum, and the extraction wavelength was 565 nm.

Accordingly, a range of the distance p between the centers of theconcave portions within a region surrounded by the coordinates A to Jcorresponding to the extraction wavelength of 565 nm was 280 nm to 416nm.

In the bottom emission type organic light emitting diodes obtained inExample 3, and Comparative Examples 5 and 6, the distance between thecenters of the convex portions and the average height in themicrostructure formed on the surface of the quartz substrate are equalto the distance between the centers of the concave portions and theaverage depth in the two-dimensional periodic structure formed on asurface of the cathodic conductive layer, which is laminated on themicrostructure, on an electron transport layer side.

Accordingly, the bottom emission type organic light emitting diode ofExample 3, in which the distance between the centers of the concaveportions is 350.0 nm that is within a range of 280 nm to 416 nm, and thedepth of the concave portions is 70 nm, is within a range of theinvention. On the other hand, since the distance between the centers ofthe concave portions is 500.0 nm, the bottom emission type organic lightemitting diode of Comparative Example 6 is out of the range of theinvention.

2. Evaluation of Luminous Efficiency Characteristics and LuminanceCharacteristics

With respect to each of the bottom emission type organic light emittingdiodes obtained in Example 3, and Comparative Examples 5 and 6, theluminous efficiency characteristics and luminance characteristics wereevaluated in the same manner as Test Example 1.

In addition, a progress rate of measurement values of Example 3 againstmeasurement values of Comparative Example 5 was calculated in the samemanner as Test Example 1. Similarly, with respect to the ComparativeExample 6, a progress rate of measurement values thereof against themeasurement values of Comparative Example 5 was also calculated. Theresults are shown in Table 2.

TABLE 2 Microstructure of Evaluation of characteristics substratesurface Luminous efficiency Luminance Distance Height Against Againstbetween (or Measurement comparative Measurement comparative centersdepth) value example value example [nm] [nm] [lm/W] [%] [cd/cm²] [%]Example 3 350.0 70 6.13 +156.5 1270 +179.7 Comparative — — 2.39 — 454 —Example 5 Comparative 500.0 70 2.86  +19.7 463  +2.0 Example 6 * Currentdensity: 7.0 mA/cm²

As shown in the results, in the bottom emission type organic lightemitting diodes of Example 3, emission intensity greatly increasedcompared to Comparative Examples 5 and 6. Furthermore, currentdensity−luminous efficiency characteristics, and currentdensity−luminance characteristics were greatly improved.

Example 4

A bottom emission type organic light emitting diode was obtained by thesame operation as Example 1 except that the substrate was prepared bychanging the average particle size of the spherical colloidal silica andthe dry etching conditions, a material obtained by doping KLHS-04 withFIlpic in a concentration of 8% was used as a light emitting material,and the cathodic conductive layer was formed with Al.

At this time, the distance between the centers of the convex portions ofthe microstructure formed on the surface of the quartz substrate was300.0 nm, and the average height of the convex portions was 31.2 nm.

Comparative Example 7

A bottom emission type organic light emitting diode was obtained by thesame operation as Example 4 except that the microstructure was notformed on the surface of the quartz substrate. Accordingly, thesubstrate surface of this element was flat.

Comparative Example 8

A bottom emission type organic light emitting diode, which was preparedby the same operation as Example 4 except that the average particle sizeof the spherical colloidal silica and the dry etching conditions werechanged, was obtained.

At this time, the distance between the centers of convex portions of themicrostructure formed on the surface of the quartz substrate was 395.0nm, and the average height of the convex portions was 30.2 nm.

Test Example 3 1. Preparation of Graph Illustrating Relationship betweenExtraction Wavelength λ (nm) and Distance p (nm) between Centers ofConcave Portions or Convex Portions in Two-Dimensional Lattice Structurein Surface of Cathodic Conductive Layer

With respect to the bottom emission type organic light emitting diodesobtained in Example 4, and Comparative Examples 7 and 8, a half width athalf maximum W(½) of a peak in an emission spectrum of a light emittingmaterial (material obtained by doping KLHS-04 with FIlipic in aconcentration of 8%) constituting the light emitting layer was obtainedby drawing on peaks, and W(½) was 20 nm. Coordinates A′ to L′ in a casewhere W(½) was 20 nm are shown in FIG. 11.

In addition, the extraction wavelength in the configurations of thebottom emission type organic light emitting diodes obtained in Example4, and Comparative Examples 7 and 8 was obtained by waveform separationof the emission spectrum, and the extraction wavelength was 470 nm.

Accordingly, a range of the distance p between the centers of theconcave portions within a region surrounded by the coordinates A′ to L′corresponding to the extraction wavelength of 470 nm was 256 nm to 366nm.

In the bottom emission type organic light emitting diodes obtained inExample 4, and Comparative Examples 7 and 8, the distance between thecenters of the convex portions and the average height in themicrostructure formed on the surface of the quartz substrate are equalto the distance between the centers of the concave portions and theaverage depth in the two-dimensional periodic structure formed on asurface of the cathodic conductive layer, which is laminated on themicrostructure, on an electron transport layer side.

Accordingly, the bottom emission type organic light emitting diode ofExample 4, in which the distance between the centers of the concaveportions is 300.0 nm that is within a range of 256 nm to 366 nm, and thedepth of the concave portions is 31.2 nm, is within a range of theinvention. On the other hand, since the distance between the centers ofthe concave portions is 395.0 nm, the bottom emission type organic lightemitting diode of Comparative Example 8 is out of the range of theinvention.

2. Evaluation of Luminous Efficiency Characteristics and LuminanceCharacteristics

With respect to each of the bottom emission type organic light emittingdiodes obtained in Example 4, and Comparative Examples 7 and 8, theluminous efficiency characteristics and luminance characteristics wereevaluated in the same manner as Test Example 1.

In addition, a progress rate of measurement values of Example 4 againstmeasurement values of Comparative Example 7 was calculated in the samemanner as Test Example 1. Similarly, with respect to the ComparativeExample 8, a progress rate of measurement values thereof against themeasurement values of Comparative Example 7 was also calculated. Theresults are shown in Table 3.

TABLE 3 Microstructure of Evaluation of characteristics substratesurface Luminous efficiency Luminance Distance Height Against Againstbetween (or Measurement comparative Measurement comparative centersdepth) value example value example [nm] [nm] [lm/W] [%] [cd/m²] [%]Example 4 300.0 31.2 5.92 +166.7 3042 +176.0 Comparative — — 2.22 — 1102— Example 7 Comparative 395.0 30.2 2.44  +9.9 1157  +5.0 Example 8 *Current density: 11.0 mA/cm²

As shown in the results, in the bottom emission type organic lightemitting diode of Example 4, emission intensity greatly increasedcompared to Comparative Examples 7 and 8. Furthermore, currentdensity−luminous efficiency characteristics, and currentdensity−luminance characteristics were greatly improved.

INDUSTRIAL APPLICABILITY

The organic light emitting diode of the invention is excellent in lightextraction efficiency, and thus may be appropriately used in an imagedisplay device and an illuminating device that are provided with theorganic light emitting diode.

DESCRIPTION OF THE REFERENCE SYMBOLS

-   -   10, 110, 210, 310: Organic light emitting diode (bottom emission        type)    -   11, 111: Substrate    -   12: Anodic conductive layer    -   13: Organic EL layer    -   13 a: Hole implantation layer    -   13 b: Hole transport layer    -   13 c: Light emitting layer    -   13 d: Electron transport layer    -   13 e: Electron implantation layer    -   14, 214: Cathodic conductive layer    -   15, 116: Convex portion    -   16: Concave portion    -   20, 120, 220, 320: Organic light emitting diode (top emission        type)    -   21, 121: Substrate    -   22: Concave portion

1. An organic light emitting diode in which at least an anodicconductive layer formed from a transparent conductor, an organicelectroluminescence layer that includes a light emitting layercontaining an organic light emitting material, and a cathodic conductivelayer formed from Ag or an alloy containing 70% by mass or more of Agare sequentially laminated on a transparent substrate, and atwo-dimensional lattice structure, in which a plurality of concaveportions are periodically and two-dimensionally arranged, is provided ona surface of the cathodic conductive layer on an organicelectroluminescence layer side; wherein an extraction wavelength λ (nm)of light from the organic light emitting diode and a distance p (nm)between centers of the concave portions in the two-dimensional latticestructure are within a region surrounded by straight lines sequentiallyconnecting the following coordinates A, B, C, D, E, F, G, H, I, J, and Ain a graph illustrating a relationship between the light extractionwavelength and the distance; a depth of the concave portions is 12 nm to180 nm; and the two-dimensional lattice structure is a triangularlattice structure; A (λ=450, p=258+W(½)), B (λ=500, p=319+W(½)), C(λ=600, p=406+W(½)), D (λ=700, p=484+W(½)), E (λ=800, p=561+W(½)), F(λ=800, p=493−W(½)), G (λ=700, p=425−W(½)), H (λ=600, p=353−W(½)), I(λ=500, p=262−W(½)), and J (λ=450, p=110−W(½)), in which W(½) representsa half width at half maximum of a light emitting peak in a spectrum ofthe light emitting material that constitutes the light emitting layer.2. The organic light emitting diode according to claim 1, wherein thedepth of the concave portions is 15 nm to 70 nm.
 3. The organic lightemitting diode according to claim 1, wherein the shape of the concaveportions is a shape obtained by transfer of a truncated conical shape ora columnar shape on the substrate, and the depth is 15 nm to 70 nm. 4.The organic light emitting diode according to claim 1, wherein the shapeof the concave portions is a shape obtained by transfer of a sinusoidalwave shape on the substrate, and the depth is 50 nm to 160 nm.
 5. Animage display device, comprising: the organic light emitting diodeaccording to claim
 1. 6. An illuminating device, comprising: the organiclight emitting diode according to claim 1.